Including audio description in YouTube and Vimeo videos

Hi everyone!

I've got a quandary that I still haven't found a good solution for: how do
you incorporate audio description into YouTube and Vimeo videos (especially
existing ones) so that you can meet WCAG 1.2.5? All the poking around I've
done hasn't turned up an effective way to include the alternate audio track
that incorporates audio description, and YouTube, at least, apparently has
rules against posting separate versions of videos.

Would it be acceptable to create a separate audio-only track that combines
the audio from the video with the necessary audio description?

Thanks for any insight you all can give.

-- 
Annie Heckel

Lead Accessibility Auditor
Online ADA <https://onlineada.com/>