When embedding a YouTube video on a organisation's website, what is necessary to make this accessible and WCAG 2.0 AAA compliant?
It's my understanding that closed captions (toggleable subtitles) are a necessity. While YouTube can auto-generate these captions, it can have mistakes which reduce your compliance. If these captions are edited for correctness, is that enough?
Or is a full transcript required?
From my reading of the WCAG 2.0 guidelines, closed-captions are enough to meet some of the guidelines at Level A, however Level AAA (and possibly AA also?) appear to require a text alternative that is not time-based, meaning you need to provide a text transcript that the user can read at their own pace (unlike captions, which forces the user to read quite quickly).
(Think of a person new to English who can only decipher words very slowly.)
Refer to: https://www.w3.org/WAI/WCAG20/quickref/#media-equiv
Apart from the need for captions, which might be met by YouTube's auto-captioning, the other issue with meeting WCAG 2.0 (or 2.1) at AA or AAA is the requirement under criterion 1.2.5 to provide audio descriptions if your video track contains any extra information or context needed to understand the audio.
Unfortunately, as of this reply YouTube does not support a separate audio description track without additional software layered on top. So the answer is that, in general, a YouTube video without extra support can be accessible only at the A level, not AA or AAA.
