Captions (Prerecorded)
Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such.
In plain language
Any recorded video that has speech or important sound needs synchronized captions — written text that appears on screen at the same moment it's spoken.
Why it matters
People who are deaf or hard of hearing can't hear a video's audio. Captions let them read what's being said, and important sounds, at the right moment, so they can follow the video just like anyone else.
In practice
Fails this criterion
A tutorial video has spoken narration explaining each step, but no captions at all. Someone who can't hear is left with no way to follow along.
Meets this criterion
The same video has captions synced to the speech, including notes for important sounds (e.g. [music playing], [knock at the door]).
Test it yourself
Watch the site's videos with the sound off. Can you follow everything that's said and every important sound just from the captions? If there are no captions at all, this criterion fails.