Ahodges/studio video

New PR, replaces https://github.com/edx/edx-documentation/pull/42.
@lou-wang, @tymofij, @polesye, @olmar, @remyedX, and @uhanile this has been reworked significantly to reduce content to only what is different about the process for course teams using the new workflow. Thoroughly reviewed by @rjgrubb .
@nasthagiri, @frrrances, @WatsonEmily , @srpearce , @mhoeber, @catong FYI.