That would require creating transcriptions. The C9 guys discussed this before, and dismissed it, claiming it would take too long to do.
You don't have to wait for the admins to add a feature or reject features, you can make them yourself. There are some video transcriptions
here and the more of these transcriptions we C9 users make, the more this guy can translate them into egyptian then he can edit the videos, add subtitles, and distribute them
to his work mates if the C9 Team allow him to edit/distribute them.
C'mon C9ers, lets help our fellow C9ers