Document:

<PAGE>

                                                                   Exhibit 10.15

                  AMENDMENT TO AFFILIATE REGISTRATION AGREEMENT

     This Amendment (the "Amendment") is executed on and entered into as of
November 10, 1994 among AV Alarm, Inc., a Texas corporation (the "Company") and
James R. Hull (the "Shareholder").

                                    Recitals:

     The Company and the Shareholder have entered into an Affiliate Registration
Agreement (the "Registration Agreement") dated as of October 21, 1994. The
Company desires to enter into Warrant Agreement (the "Warrant Agreement") with
Heller Financial, Inc., a Delaware corporation ("Heller"). The Company desires
to grant certain registration rights to the holders of warrants granted pursuant
to the Warrant Agreement. The Company and the Shareholder desire to amend
certain provisions in the Registration Agreement.

     The parties agree as follows:

     1. Amendments. Paragraphs 1(c) and 1(d) of the Registration Agreement are
hereby amended to read in its entirety as follows:

               "(c) Priority on Primary Registrations. If a Piggyback
          Registration relates to an underwritten public offering of equity
          securities by the Company and the managing underwriters advise the
          Company in writing that in their opinion the number of securities
          requested to be included in such registration exceeds the number which
          can be sold in an orderly manner in such offering within a price range
          acceptable to the Company, the Company will include in such
          registration (i) first, the securities proposed to be sold by the
          Company, (ii) second, the Issued Warrant Shares (as defined in the
          Warrant Agreement), (iii) third, the Underlying Common Stock requested
          to be included in such registration, pro rata among the holders of
          such Underlying Common Stock on the basis of the number of shares
          owned by each such holder, (iv) fourth, securities other than
          Underlying Common Stock requested to be included in such registration
          by holders of Underlying Common Stock and non-Purchaser Affiliates,
          and (v) fifth, other securities requested to be included in such
          registration.

               (d) Priority on Secondary Registrations. If a Piggyback
          Registration relates to an underwritten public offering of equity
          securities by holders of the Company's securities and the managing
          underwriters advise the Company in writing that in their opinion the
          number of securities requested to be included in such registration
          exceeds the number which can be sold in an orderly manner in such
          offering within a price range acceptable to the holders initially
          requesting such registration, the Company will include in such
          registration (i) first, the Issued Warrant Shares, (ii) second, the
          securities requested to be included therein by the holders requesting
          such registration, (iii) third, the Underlying Common Stock requested
          to be included in such registration, pro rata among the holders of
          such Underlying Common Stock on the basis of the number of shares
          owned by each such holder, (iv) fourth, securities other than
          Underlying Common Stock

<PAGE>

          requested to be included in such registration by holders of Underlying
          Common Stock and non-Purchaser Affiliates, and (v) fifth, other
          securities requested to be included in such registration."

All other provisions of the Registration Agreement shall remain in full force
and effect and shall not be deemed altered or amended by reason of any provision
of this Amendment.

     2. Miscellaneous.

     (a) Descriptive Headings. The descriptive headings of this Amendment are
inserted for convenience only and do not constitute a part of this Amendment.

     (b) Governing Law. The construction, validity and interpretation of this
Amendment will be governed by and construed in accordance with the domestic laws
of the State of Texas, without giving effect to any choice of law or conflict of
law provision or rule (whether of the State of Texas or any other jurisdiction)
that would cause the application of the laws of any jurisdiction other than the
State of Texas.

Counterparts. This Amendment may be executed in any number of counterparts and
by different parties hereto in separate counterparts, with the same effect as if
all parties had signed the same document. All such counterparts shall be deemed
an original, shall be construed together and shall constitute one and the same
instrument.

                                      * * *

                                       2

<PAGE>

                                        COMPANY:

                                        AV Alarm, Inc.

                                        By: /s/ James R. Hull
                                            ------------------------------------
                                            James R. Hull,
                                            President

                                        PURCHASERS:

                                        Austin Ventures III-A, L.P.

                                        By AV Partners III, L.P.
                                        Its General Partner

                                        By:
                                            ------------------------------------
                                            Blaine F. Wesner,
                                            Authorized Signatory

                                        Austin Ventures III-B, L.P.

                                        By AV Partners III, L.P.
                                        Its General Partner

                                        By:
                                            ------------------------------------
                                            Blaine F. Wesner,
                                            Authorized Signatory

                                       3

<PAGE>

                                                    COMPANY:

                                                    AV Alarm, Inc.

                                                    By:
                                                        ------------------------
                                                        James R. Hull,
                                                        President

                                                    PURCHASERS:

                                                    Austin Ventures III-A, L.P.

                                                    By AV Partners III, L.P.
                                                    Its General Partner

                                                    By: /s/ Blaine F. Wesner
                                                        ------------------------
                                                        Blaine F. Wesner,
                                                        Authorized Signatory

                                                    Austin Ventures III-B, L.P.

                                                    By AV Partners III, L.P.
                                                    Its General Partner

                                                    By: /s/ Blaine F. Wesner
                                                        ------------------------
                                                        Blaine F. Wesner,
                                                        Authorized Signatory

                                       3<PAGE>

                                                                   Exhibit 10.16

                  THIRD AMENDED AND RESTATED CO-SALE AGREEMENT

     This Third Amended and Restated Co-Sale Agreement (the "Agreement") is
entered into as of January 18, 2002 by and among Monitronics International,
Inc., a Texas corporation (the "Company"), the holders of Preferred Stock listed
on the Schedule of Preferred Holders attached hereto (the "Preferred Holders"),
the holders of Common Stock Purchase Warrants listed on the Schedule of Warrant
Holders attached hereto (the "Warrant Holders," and collectively with the
Preferred Holders, the "Purchasers"), the holders of Common Stock listed on the
Schedule of Common Shareholders attached hereto (the "Common Shareholders," and,
together with the Purchasers and such other parties as may from time to time
become parties hereto, the "Shareholders").

                                    Recitals

     The Company and certain of the Preferred Holders are parties to a Stock
Purchase Agreement, dated as of October 21, 1994, as amended by that certain
Amendment No. 1 to Stock Purchase Agreement, dated as of November 10, 1994, that
certain Amendment No. 2 to Stock Purchase Agreement, dated as of May 10, 1996,
that certain Amendment Agreement, dated as of November 22, 1996 (the "First
Amendment Agreement"), that certain Second Amendment Agreement, dated as of May
19, 1997 (the "Second Amendment Agreement"), that certain Transfer, Assignment
and Assumption Agreement and Third Amendment Agreement, dated as of January 1,
1998 (the "Third Amendment Agreement"), that certain Consent to Various Actions
under Various Documents, dated as of May 13, 1998, that certain Consent to
Various Actions under Various Documents and Amendment to Stock Purchase
Agreement, dated as of January 6, 1999, that certain Sixth Amendment Agreement
dated as of April 27, 2001 (the "Sixth Amendment Agreement") and that certain
Seventh Amendment Agreement dated as of January 18, 2002 (the "Seventh Amendment
Agreement") (as so amended, the "Series A Purchase Agreement"), providing, among
other things, for the purchase by such Preferred Holders of 4,000,000 shares of
Series A Preferred Stock of the Company.

     The Company and certain of the Warrant Holders are parties to a Senior
Subordinated Note and Warrant Purchase Agreement, dated as of May 10, 1996, as
supplemented and modified by (i) the Senior Subordinated Note and Warrant
Purchase Agreement, dated as of November 22, 1996, and (ii) the Senior
Subordinated Note and Warrant Purchase Agreement, dated as of May 19, 1997, as
amended by that certain Amendment, dated as of March 13, 1998, that certain
Second Amendment, dated as of January 13, 1999, that certain Termination of Put
Rights, dated as of June 15, 1998, that certain Third Amendment, dated as of
March 9, 1999, and that certain Fourth Amendment, dated as of February 4, 2000,
(iii) the Sixth Amendment Agreement and (iv) the Seventh Amendment Agreement (as
so supplemented and modified, the "Note Agreement"), providing, among other
things, for the purchase by such Warrant Holders of warrants (the "Mezzanine
Warrants") to acquire up to 569,757 shares (subject to adjustment as provided in
such Warrants) of Class A Common Stock of the Company.

     The Company and certain of the Preferred Holders are parties to a Series B
Preferred Stock Purchase Agreement, dated as of May 19, 1997, as amended by the
Third Amendment Agreement, that certain Termination of Put Rights, dated as of
June 15, 1998 and the Seventh Amendment Agreement (as so amended, the "Series B
Purchase Agreement"), providing, among

<PAGE>

other things, for the purchase by such Preferred Holders of 5,000,000 shares of
Series B Preferred Stock and warrants (the "Preferred B Warrants") to acquire up
to 961,700 shares (subject to adjustment as provided in such Warrants) of Class
A Common Stock of the Company.

     The Company and certain of the Preferred Holders are parties to a Series C
Preferred Stock Purchase Agreement, dated as of February 22, 1999, providing,
among other things, for the purchase by certain Preferred Holders of 1,409,375
shares of Series C Preferred Stock of the Company.

     The Company and certain of the Preferred Holders are parties to a Series C
Preferred Stock Exchange Agreement, dated as of April 27, 2001, providing, among
other things, for the exchange by certain Preferred Holders of 1,409,375 shares
of Series C Preferred Stock of the Company for 1,409,375 shares of Series C
Preferred Stock and 251,420 shares of Series C-1 Preferred Stock of the Company.

     The Company and certain of the Preferred Holders have entered into a Series
D-1 Preferred Stock Purchase Agreement, dated as of April 27, 2001, as amended
by that certain First Amendment to Series D-1 Preferred Stock Purchase
Agreement, dated as of January 18, 2002 (the "Series D-1 Purchase Agreement"),
providing, among other things, for the purchase by certain Preferred Holders of
up to 70,000 shares of Series D-1 Preferred Stock.

     The Company and certain of the Warrant Holders are parties to a
Subordinated Note and Warrant Purchase Agreement, dated as of January 18, 2002
("2001 Note Agreement"), providing, among other things, for the purchase by such
Warrant Holder of warrants (the "2001 Warrants" and, together with the Mezzanine
Warrants and the Preferred B Warrants, the "Warrants") to acquire up to
1,133,328 shares (subject to adjustment as provided in such Warrants) of Class A
Common Stock of the Company.

     The Company, the Preferred Holders referred to therein, the Warrant Holders
referred to therein and each Common Shareholder are parties to a Second Amended
and Restated Co-Sale Agreement, dated as of April 27, 2001(as amended, the
"Second Amended and Restated Co-Sale Agreement").

     The parties hereto are, concurrently herewith, entering into a Fourth
Amended and Restated Shareholders Agreement, dated as of the date hereof (as in
effect from time to time, the "Shareholders Agreement").

     The parties hereto desire to amend and restate the Second Amended and
Restated Co-Sale Agreement in its entirety in order to facilitate the
transactions contemplated by the 2001 Note Agreement.

     Capitalized terms not defined elsewhere herein shall have the respective
meanings assigned to them in the Shareholders Agreement.

     The parties hereto agree that the Second Amended and Restated Co-Sale
Agreement shall be amended and restated in its entirety by this Agreement, and
the parties further agree as follows:

                                       2

<PAGE>

1.   Co-Sale Provisions.

     1A. Co-Sale Right. Subject to Paragraph 1C of this Agreement, whenever and
as often as any party hereto (a "Selling Shareholder") desires to sell any
Series A Preferred Stock, Series C Preferred Stock, Warrant Shares or Common
Stock ("Triggering Securities"), the Selling Shareholder shall give written
notice (the "Selling Shareholder Notice") to each other party hereto that is a
holder of Company Securities and each Permitted Transferee thereof that is a
holder of Company Securities (each, an "Offeree Shareholder") to such effect,
enclosing a copy of the written offer (or, if no written offer exists, a
detailed written summary of such unwritten offer) specifying the number and type
of Triggering Securities which the Selling Shareholder desires to sell (and, in
the case of Triggering Securities other than Common Stock, the number of shares
of Common Stock such Triggering Securities are convertible into, or exercisable
or exchangeable for), the name of the Person(s) to whom the Selling Shareholder
desires to make such sale and the purchase price per share of Triggering
Securities which has been offered in connection with such offer. Each Offeree
Shareholder shall have the right, at such Offeree Shareholder's option, either
to (a) exercise its rights, if any, under Paragraph 2B of the Shareholders
Agreement (if such Paragraph 2B applies to such sale) or (b) to participate in
the sale to the prospective purchaser pursuant to this Paragraph 1 (the "Co-Sale
Right").

     1B. Exercise of Co-Sale Right. An Offeree Shareholder may exercise his or
its Co-Sale Right by giving written notice (the "Offeree Shareholder Notice") to
the Selling Shareholder within 20 days after the receipt of the Selling
Shareholder Notice. If any Offeree Shareholder exercises his or its Co-Sale
Right, the Selling Shareholder shall arrange for the sale to the prospective
purchaser of up to a quantity of Company Securities (including, in the case of a
sale of Common Stock or Company Securities convertible into, or exercisable or
exchangeable for, Common Stock, shares of Common Stock issuable upon the
conversion, exercise or exchange of such Company Securities) of each Offeree
Shareholder delivering an Offeree Shareholder Notice which bears the same
proportion to the total number of shares of Common Stock (on a fully-diluted
basis) owned by such Offeree Shareholder as the number of shares of Common Stock
(on a fully-diluted basis) being sold by the Selling Shareholder bears to the
total number of shares of Common Stock (on a fully-diluted basis) owned by the
Selling Shareholder, at the purchase price per share and on the terms and
conditions specified in the Selling Shareholder Notice. For purposes of this
Paragraph 1B:

          (a) if the Selling Shareholder proposes to sell only Common Stock, an
Offeree Shareholder may elect to sell (i) Common Stock (1) held by such Offeree
Shareholder and/or (2) issuable to such Offeree Shareholder upon the conversion,
exercise or exchange of other Company Securities held by such Offeree
Shareholder, at the purchase price per share specified for the Common Stock in
the Selling Shareholder Notice, and/or (ii) Company Securities held by such
Offeree Shareholder which are convertible into, or exercisable or exchangeable
for, Common Stock, at the purchase price per share of Common Stock specified in
the Selling Shareholder Notice multiplied by the number of shares of Common
Stock into which a share of such Company Securities are then convertible into,
or exercisable or exchangeable for;

          (b) if the Selling Shareholder proposes to sell only Preferred Stock,
an Offeree Shareholder may elect to sell (i) Preferred Stock of the same series
as that being sold by the Selling Shareholder held by such Offeree Shareholder,
at the purchase price per share specified

                                       3

<PAGE>

for the Preferred Stock in the Selling Shareholder Notice and/or (ii) Common
Stock (1) held by such Offeree Shareholder and/or (2) issuable to such Offeree
Shareholder upon the conversion, exercise or exchange of other Company
Securities held by such Offeree Shareholder, at a price determined by dividing
(A) (x) the purchase price per share of the Preferred Stock specified in the
Selling Shareholder Notice minus (y) if the Preferred Stock to be sold by the
Selling Shareholder is Series A Preferred Stock, the Series A Liquidation Value
(as defined in the Articles of Incorporation) per share of the Series A
Preferred Stock as of the date of the sale by (B) the number of shares of Common
Stock into which a share of the Preferred Stock to be sold by the Selling
Shareholder is then convertible; and

          (c) if the Selling Shareholder proposes to sell Preferred Stock and
Common Stock, an Offeree Shareholder may elect to sell (i) Preferred Stock of
the same series as that being sold by the Selling Shareholder held by such
Offeree Shareholder at the purchase price per share specified for the Preferred
Stock in the Selling Shareholder Notice and/or (ii) Common Stock (1) held by
such Offeree Shareholder and/or (2) issuable to such Offeree Shareholder upon
the conversion, exercise or exchange of Company Securities held by such Offeree
Shareholder, at a price determined by dividing (A) (x) the purchase price per
share of the Preferred Stock specified in the Selling Shareholder Notice minus
(y) if the Preferred Stock to be sold by the Selling Shareholder is Series A
Preferred Stock, the Series A Liquidation Value (as defined in the Articles of
Incorporation) per share of the Series A Preferred Stock as of the date of the
sale by (B) the number of shares of Common Stock into which a share of the
Preferred Stock to be sold by the Selling Shareholder is then convertible;
provided, that the reduction described in clause (A)(y) above will apply only to
a proportion of the Common Stock to be included by an Offeree Shareholder that
is equal to the proportion that the Series A Preferred Stock (on an as-converted
basis), to be included by the Selling Shareholder bears to the total quantity of
Common Stock and Preferred Stock (on an as-converted basis) to be included by
the Selling Shareholder.

     1C. Immediate Vesting of Company Securities; Excluded Transactions. For
purposes of this Part 1, Company Securities that are convertible into, or
exercisable or exchangeable for, Common Stock, at such Offeree Shareholder's
option, shall vest immediately prior to the closing of the sale of the shares of
Company Securities by the Selling Shareholder pursuant to this Part 1 so that
such shares may be issued and sold hereunder by such Offeree Shareholder and
shall be considered issued and outstanding for purposes of making the above
calculations. The Co-Sale Right shall not apply to (a) the repurchase or
redemption by the Company of any Company Securities, (b) any event which is a
"liquidation" (as defined in the Articles of Incorporation), (c) transfers of
Company Securities to any Permitted Transferee, provided such Permitted
Transferee complies with the provisions of Paragraph 1D(ii) of this Agreement,
(d) a pledge of Company Securities to the Lenders as acknowledged by the parties
hereto pursuant to Paragraph 5M of the Shareholders Agreement, (e) transfers of
Preferred B Warrant Shares, provided such Preferred B Warrant Shares are
transferred as part of a transaction in which not less than a proportional
amount of the shares of Series B Preferred Stock held by the transferring holder
and its Affiliates are also transferred or (f) transfers of shares of Series D
Underlying Common Stock, provided such shares of Series D Underlying Common
Stock are transferred as part of a transaction in which not less than a
proportional amount of the shares of Series D-2 Preferred Stock held by the
transferring holder and its Affiliates are also transferred.

                                       4

<PAGE>

     1D. Purchasers or Transferees of Capital Stock. Except as otherwise
specifically provided herein, any transferee or other Person who shall acquire
(either voluntarily or involuntarily, by operation of law or otherwise) any
shares of Company Securities that were originally held by a party to this
Agreement shall be bound by, and shall have the benefit of, all the terms and
conditions of this Agreement to the same extent as such party. The Company shall
not effect any such transfer of Company Securities until: (i) it has received
evidence satisfactory to it that all of the provisions of this Agreement
applicable to such transfer have been complied with and (ii) each transferee or
other Person (and such transferee's or other Person's spouse) of such Company
Securities has executed an addendum agreement with the parties hereto in the
form of Exhibit A attached hereto, agreeing to be bound hereby. Each transferee
of, or other Person acquiring, Company Securities shall take such Company
Securities subject to, and be fully bound by, this Agreement with the same
effect as if it were a party hereto, with those rights and obligations hereunder
expressly provided herein.

2.   General Provisions.

     2A. Legends on Certificates.

          (a) During the term of this Agreement, the Company shall affix to each
certificate issued on or after the date hereof to a party hereto and evidencing
Triggering Securities, a legend in substantially the following form:

          "THE SECURITIES REPRESENTED BY THIS CERTIFICATE AND THE SALE,
          ASSIGNMENT, TRANSFER, PLEDGE OR OTHER DISPOSITION THEREOF ARE SUBJECT
          TO CERTAIN RESTRICTIONS AND AGREEMENTS CONTAINED IN A THIRD AMENDED
          AND RESTATED CO-SALE AGREEMENT DATED AS OF JANUARY 18, 2002 AMONG THE
          COMPANY AND CERTAIN SHAREHOLDERS AND WARRANT HOLDERS. A COPY OF THE
          CO-SALE AGREEMENT AND ALL APPLICABLE AMENDMENTS THERETO WILL BE
          FURNISHED BY THE COMPANY TO THE RECORD HOLDER OF THIS CERTIFICATE
          WITHOUT CHARGE UPON WRITTEN REQUEST TO THE COMPANY AT ITS PRINCIPAL
          PLACE OF BUSINESS OR REGISTERED OFFICE."

          (b) During the term of this Agreement, the Company shall not effect
any transfer of Triggering Securities evidenced by a certificate issued prior to
the date hereof and held by any party to this Agreement until it has advised the
proposed transferee of such Triggering Securities that such Triggering
Securities are subject to the restrictions on transfer set forth in this
Agreement and provided such proposed transferee with a copy of this Agreement
and any applicable amendments. The Company shall make a notation on its records
and give instructions to any transfer agent of the Company Securities in order
to implement the restrictions on transfer established in this Agreement.

                                       5

<PAGE>

     2B. Termination; Amendment and Waiver.

          (a) This Agreement shall terminate upon the earlier to occur of (i)
the written agreement of (A) the holders of at least 66 2/3% of the Series A
Underlying Common Stock then outstanding, (B) the holders of at least 66 2/3% of
the Warrant Shares (other than the 2001 Warrant Shares), (C) the holders of at
least 66 2/3% of the Series C Underlying Common Stock then outstanding, (D) the
holders of at least 66 2/3% of the Series D Underlying Common Stock then
outstanding, and (E) the holders of at least 66 2/3% of the 2001 Warrant Shares
then outstanding, (ii) the acquisition by a single purchaser of all of the
issued and outstanding shares of the Preferred Stock, Underlying Common Stock,
Common Stock, Warrants and Warrant Shares or (iii) the closing of a Qualified
Public Offering.

          (b) No amendment, modification or waiver of this Agreement or any
provision hereof shall be effective unless made by the written agreement of (A)
the holders of at least 66 2/3% of the Series A Underlying Common Stock then
outstanding, (B) the holders of at least 66 2/3% of the Warrant Shares (other
than the 2001 Warrant Shares), (C) the holders of at least 66 2/3% of the Series
C Underlying Common Stock then outstanding, (D) the holders of at least 66 2/3%
of the Series D Underlying Common Stock then outstanding, and (E) the holders of
at least 66 2/3% of the 2001 Warrant Shares then outstanding.

     2C. Notices. All notices, demands or other communications to be given or
delivered under or by reason of the provisions of this Agreement will be in
writing and will be deemed to have been given when delivered personally or by
cable, telex, facsimile transmission, telegram or overnight delivery service, or
72 hours after having been mailed by certified or registered mail, return
receipt requested and postage prepaid, to the recipient. Such notices, demands
and other communications will be sent to each party at the address indicated
below:

To the Company:   Monitronics International, Inc.
                  12801 Stemmons Freeway
                  Suite 821
                  Dallas, TX 75234
                  Facsimile: (972) 919-1985
                  Attn: James R. Hull

With a copy to:   Vinson & Elkins L.L.P.
                  2001 Ross Avenue
                  Suite 3700
                  Dallas, TX 75201
                  Facsimile: (214) 999-7714
                  Attn: Christine Hathaway

     To Preferred Holders or Warrant Holders to their addresses set forth on the
Schedule of Preferred Holders or Warrant Holders, as the case may be,

                                       6

<PAGE>

With a copy to:   If to Austin Ventures:
                  Vinson & Elkins L.L.P.
                  600 Congress Avenue
                  Suite 2700
                  Austin, TX 78701
                  Facsimile: (512) 236-3450
                  Attn: William R. Volk

                  and

                  If to Windward:
                  Skadden, Arps, Slate, Meagher & Flom LLP
                  Four Times Square
                  New York, NY 10036
                  Facsimile: (212) 735-2000
                  Attn: Howard L. Ellin

                  and

                  If to ABRY:
                  Kirkland & Ellis
                  153 East 53rd Street
                  New York, NY 10022
                  Facsimile: (212) 446-4900
                  Attn: John L. Kuehn

                  and

                  If to CRL:
                  Testa, Hurwitz & Thibeault, LLP
                  125 High Street
                  Boston, MA 02110
                  Facsimile: (617) 248-7100
                  Attn: Andrew E. Taylor, Jr.

                  and

                  If to The Northwestern Mutual Life Insurance Company:
                  Schiff Hardin & Waite
                  6600 Sears Tower
                  Chicago, IL 60606
                  Facsimile: (312) 258-5600
                  Attn: Andrew A. Kling

                                       7

<PAGE>

     To the Common Shareholders, to their addresses set forth on the Schedule of
Common Shareholders, or to such other address or to the attention of such other
Person as the recipient party has specified by prior written notice to the
sending party.

     2D. Governing Law. The construction, validity and interpretation of this
Agreement will be governed by the internal laws of the State of Texas without
giving effect to any choice of law or conflict of law provision or rule (whether
of the State of Texas or any other jurisdiction) that would cause the
application of the laws of any jurisdiction other than the State of Texas.

     2E. Entire Agreement. This Agreement and the addendum, exhibits and
schedules hereto embody the entire agreement and understanding between the
parties hereto with respect to the subject matter hereof and supersedes all
prior agreements and understandings relating to such subject matter.

     2F. Further Assurances. Each party to this Agreement hereby covenants and
agrees, without the necessity of any further consideration, to execute and
deliver any and all such further documents and take any and all such other
actions as may be necessary or appropriate to carry out the intent and purposes
of this Agreement and to consummate the transactions contemplated herein.

     2G. Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which shall
be one and the same document.

     2H. Reorganization. The provisions of this Agreement shall apply to any
shares of Equity Securities resulting from any stock split or reverse stock
split, stock dividend, reclassification, subdivision, consolidation or
reorganization of any shares of Company Securities and to any shares of Company
Securities or shares of Equity Securities of any successor company which may be
received by any of the parties hereto by virtue of their respective ownership of
any shares of Company Securities.

     2I. Descriptive Headings. The descriptive headings of this Agreement are
inserted for convenience only and do not constitute a part of this Agreement.

     2J. Severability. Whenever possible, each provision of this Agreement will
be interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Agreement is held to be prohibited by or invalid
under applicable law, such provision will be ineffective only to the extent of
such prohibition or invalidity, without invalidating the remainder of this
Agreement.

     2K. Binding Effect. Except as otherwise expressly provided herein, all
covenants and agreements in this Agreement by or on behalf of any of the parties
hereto will bind and inure to the benefit of the respective heirs, personal
representatives, successors and assigns of the parties hereto whether so
expressed or not. In addition, and whether or not any express assignment has
been made, unless expressly provided otherwise, the provisions of this Agreement
which are for (i) any Purchaser's benefit as a purchaser or holder of shares of
Underlying Common Stock are also for the benefit of, and enforceable by, any
subsequent holder of such Underlying Common Stock and (ii) any Warrant Holder's
benefit as a purchaser or holder of Warrants and/or Warrant Shares are also for
the benefit of, and enforceable by, any subsequent holder of such Warrants

                                       8

<PAGE>

and/or Warrant Shares. Except as provided in this Paragraph 2K, for assignments
of rights and obligations to a transferee of shares of Company Securities or by
operation of law, no party hereto shall make any assignment or transfer of any
of its rights or obligations hereunder without the prior written consent of each
of the other parties hereto, unless such assignment or transfer is to a
Permitted Transferee of such party.

     2L. Exception for Pledge. The parties acknowledge that pursuant to the
terms of a (a) Third Amended and Restated Pledge Agreement, dated as of January
13, 1999, as amended to date (the "Pledge Agreement"), by and between Austin
Ventures III, Austin Ventures V, Capital Resource Lenders II, L.P. ("CRL"), Hull
Family Limited Partnership, Robert Sherman, individually, Michael Gregory,
individually, Michael Meyers, individually, and Stephen Hedrick, individually
(collectively, the "Pledgors") and Canadian Imperial Bank of Commerce, as
Administrative Agent, State Street Bank and Trust Company, for itself and as
Documentation and Collateral Agent (the "Secured Party"), CIBC, Inc., Heller
Financial, Inc., Chase Bank of Texas, National Association, Union Bank of Texas,
N.A., Wells Fargo Bank (Texas) National Association, LaSalle National Bank and
BankBoston, N.A. (collectively, the "Lenders"), (b) Pledge Agreement, dated as
of April 27, 2001, as amended to date (the "ABRY/Windward/CRL Pledge
Agreement"), by and between ABRY, Windward, CRL and the Lenders and (c) Pledge
Agreement, dated as of January 18, 2002 (the "NML Pledge Agreement"), by and
between The Northwestern Mutual Life Insurance Company ("NML") and the Lenders,
certain Company Securities, as identified on Schedule I to the Pledge Agreement,
the ABRY/Windward/CRL Pledge Agreement and the NML Pledge Agreement
(collectively, the "Pledged Securities"), have been pledged by the Pledgors,
ABRY, Windward, CRL and NML to the Secured Party for the benefit of the Lenders.
The parties hereto acknowledge and consent to such pledge of the Pledged
Securities and, notwithstanding any provision in this Agreement to the contrary,
hereby agree that any purchaser of such Pledged Securities, including the
Lenders, who acquires the Pledged Securities pursuant to the terms of the Pledge
Agreement, the ABRY/Windward/CRL Pledge Agreement and the NML Pledge Agreement
shall take the Pledged Securities free and clear of all terms of this Agreement
and neither such Persons nor such Pledged Securities shall thereafter be subject
to any term or condition of this Agreement.

                                     * * * *

                                       9

<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Agreement as of the date
first above written.

                                        COMPANY:

                                        MONITRONICS INTERNATIONAL, INC.

                                        By: /s/ James R. Hull
                                            ------------------------------------
                                            James R. Hull,
                                            President

                                        PURCHASERS:

                                        AUSTIN VENTURES III-A, L.P.

                                        By: AV Partners III, L.P.,
                                            Its General Partner

                                            By: /s/ Blaine F. Wesner
                                                --------------------------------
                                                Blaine F. Wesner,
                                                Authorized Signatory

                                        AUSTIN VENTURES III-B, L.P.

                                        By: AV Partners III, L.P.,
                                            Its General Partner

                                            By: /s/ Blaine F. Wesner
                                                --------------------------------
                                                Blaine F. Wesner,
                                                Authorized Signatory

                                        AUSTIN VENTURES V, L.P.

                                        By: AV Partners V, L.P.,
                                            Its General Partner

                                            By: /s/ Blaine F. Wesner
                                                --------------------------------
                                                Blaine F. Wesner,
                                                General Partner

<PAGE>

                                        AUSTIN VENTURES V AFFILIATES FUND, L.P.

                                        By: AV Partners V, L.P.,
                                            Its General Partner

                                            By: /s/ Blaine F. Wesner
                                                --------------------------------
                                                Blaine F. Wesner,
                                                General Partner

                                        CAPITAL RESOURCE LENDERS II, L.P.

                                        By: Capital Resource Partners II, L.P.,
                                            Its General Partner

                                            By: /s/ Stephen M. Jenks
                                                --------------------------------
                                                General Partner

                                        WINDWARD CAPITAL PARTNERS II, L.P.

                                        By: Windward Capital GP II, LLC,
                                            Its General Partner

                                        By: /s/ Peter S. Macdonald
                                            ------------------------------------
                                            Peter S. Macdonald,
                                            Managing Member

                                        WINDWARD CAPITAL LP II, LLC

                                        By: /s/ Peter S. Macdonald
                                            ------------------------------------
                                            Peter S. Macdonald,
                                            Managing Member

<PAGE>

                                        ABRY PARTNERS IV, L.P.

                                        By: ABRY Capital Partners, L.P.,
                                            Its General Partner

                                            By: ABRY Capital Partners, LLC,
                                                Its General Partner

                                                By /s/ illegible signature
                                                   -----------------------------
                                                   Name:
                                                   Title: Authorized Agent

                                        ABRY INVESTMENT PARTNERSHIP, L.P.

                                        By: ABRY Investment GP, LLC,
                                            Its General Partner

                                            By: /s/ illegible signature
                                                --------------------------------
                                                Name:
                                                Title: Authorized Agent

                                        THE NORTHWESTERN MUTUAL LIFE
                                        INSURANCE COMPANY

                                        By: /s/ Jeffrey J. Lueken
                                            ------------------------------------
                                            Name:
                                            Title: Authorized Agent

                                        COMMON SHAREHOLDERS:

                                        HULL FAMILY LIMITED PARTNERSHIP, L.P.

                                        By: James R. Hull Management Trust,
                                            Its General Partner

                                            By: /s/ James. R. Hull
                                                --------------------------------
                                                James R. Hull, Trustee

                                        /s/ Robert N. Sherman
                                        ----------------------------------------
                                        Robert N. Sherman

<PAGE>

                                    EXHIBIT A

                     Addendum Agreement to Co-Sale Agreement

     This Addendum Agreement is executed on and effective as of ______________,
by and among _____________ (the "New Shareholder"), the New Shareholder's Spouse
(if any), and Monitronics International, Inc., a Texas corporation (the
"Company").

     The Third Amended and Restated Co-Sale Agreement, dated as of January 18,
2002 (the "Co-Sale Agreement"), among the Company and certain shareholders of
the Company provides that all persons prior to becoming shareholders of the
Company must enter into an Addendum Agreement binding such person and such
person's spouse (if any) to the Co-Sale Agreement to the same extent as if they
were original parties thereto.

     Therefore, the New Shareholder and the spouse of the New Shareholder (if
any) hereby agree to be bound by all terms and conditions of the Co-Sale
Agreement to the same extent as if they were original signatories to the Co-Sale
Agreement. This Addendum Agreement shall be attached to and become part of the
Co-Sale Agreement.

                                        NEW SHAREHOLDER:

                                        ----------------------------------------
                                        Signature

                                        ----------------------------------------
                                        Spouse of New Shareholder

                                        COMPANY:

                                        Monitronics International, Inc.

                                        By:
                                            ------------------------------------
                                        Title:

                                      A-1

<PAGE>

                          SCHEDULE OF PREFERRED HOLDERS

Austin Ventures III-A, L.P.
Austin Ventures III-B, L.P.
Austin Ventures V, L.P.
Austin Ventures V Affiliates Fund, L.P.
701 Brazos
Suite 1400
Austin, TX 78701
Facsimile: (512) 476-3952
Attn: Blaine F. Wesner

Capital Resource Lenders II, L.P.
c/o Capital Resource Partners
85 Merrimac Street
Suite 200
Boston, MA 02114
Facsimile: (617) 723-9819
Attn: Stephen M. Jenks

Windward Capital Partners II, L.P.
Windward Capital II L.P., LLC
1177 Avenue of the Americas
42nd Floor
New York, NY 10036
Facsimile: (212) 382-6534
Attn: Peter S. Macdonald

ABRY Partners IV, L.P.
ABRY Investment Partnership, L.P.
18 Newbury Street
Boston, MA 02116
Facsimile: (617) 859-7205
Attn: Jay Grossman

<PAGE>

                           SCHEDULE OF WARRANT HOLDERS

Capital Resource Lenders II, L.P.
c/o Capital Resource Partners
85 Merrimac Street
Suite 200
Boston, MA 02114
Facsimile: (617) 723-9819
Attn: Stephen M. Jenks

Austin Ventures III-A, L.P.
Austin Ventures III-B, L.P.
Austin Ventures V, L.P.
Austin Ventures V Affiliates Fund, L.P.
701 Brazos
Suite 1400
Austin, TX 78701
Facsimile: (512) 476-3952
Attn: Blaine F. Wesner

The Northwestern Mutual Life Insurance Company
720 East Wisconsin Avenue
Milwaukee, WI 53202
Facsimile: (414) 299-7124
Attn: Securities Department

<PAGE>

                         SCHEDULE OF COMMON SHAREHOLDERS

1.   Hull Family Limited Partnership, L.P.
     c/o Monitronics International, Inc.
     12801 Stemmons Freeway
     Suite 821
     Dallas, TX 75234

2.   Robert N. Sherman
     c/o Monitronics International, Inc.
     12801 Stemmons Freeway
     Suite 821
     Dallas, TX 75234

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00057-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00057-of-00352.parquet"}]]