There is no requirement to include videos in any content; to video or not to video is up to the author. If you include videos, they need to follow the video standards. You may want to take a look at the video best practices as well.
Videos:
have captions & transcripts
are embedded or linked correctly
embedded video
text link to video
linked video thumbnails
use the appropriate embed code, if using YouTube
individual Videos
playlists
Create captions
Create transcripts
WCAG standard
Creating videos best practices