Changes to Step 2. Create or Obtain a Video Transcript (fixes DOC-1143)

@mslotkeEDX this changes "strongly recommended" to "required". I also did some reorganization and tweaking to this Step 2 section.
@srpearce , let me know if I introduced any errors!
@mhoeber , @catong , FYI
Nice to have this recommended --> required change in ASAP to support the PMs.