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Videos should have transcripts and captions. To achieve Level AAA compliance, videos must have an alternative that is fully available in text form and that is clearly labeled as an alternative. (An audio alternative will only achieve Level AA compliance.) Full descriptions should be provided of all visual information, including visual context, actions and expressions of actors, and any other visual material, as well as descriptions of non-speech sounds. Transcripts of all dialogue should be included. The sequence of descriptions and dialogue transcripts must be the same as the sequence in the synchronized media itself.
To ensure web accessibility, see W3C's pages on: