Clarify that download rate is in bytes per second

I found https://github.com/rg3/youtube-dl/commit/f918ec7ea29a37521d1fc22fb9f900283c5a2c49 but it is still not clear to anyone who hasn't read Issue #723 whether the limit is in bits or bytes.  This is doubly confusing because 1) ISPs usually advertise speeds in bits per second, and 2) lowercase "k" and "m" are often used in correlation with bits rather than bytes.
Extractor for websurg.com
Merge remote-tracking branch 'upstream/master' into websurg
Improvements
Restore accidentally deleted commits

That's what happens if you let Windows machines write :(
Implement more opcodes
Change test target (Verified with node.js)
Prepare signature function caching
Use reader instead of indexing
Clarify a couple of calls
[youtube] Add filesystem signature cache
[youtube] Improve cache and add an option to print the extracted signatures
Update static signatures
[youtube] Improve source code quality
[youtube] Actually pass in cachedir option
Move cachedir doc
[youtube] Remove _decrypt_signature_age_gate
Work around nosetests nosiness
[youtube] Improve flash player URL handling
Do not warn if fallback is without alternatives (because we did not get the flash player URL)