Just recently I came across a great project from the creators of my favorite video player, Miro, That is designed to make video content more accessible, it is called Amara. It is a simple free way to add subtitles to any video:
The project needs your help, users who are deaf or hard of hearing and non-profits have made specific request for help with videos that need captions or translations. Start volunteering.
For a version subtitled in dozens of languages, see universalsubtitles.org/en/videos/NmkV5cbiCqUU/info/learn-about-universal-subtitles/