[Enhancement]: Let users upload/add WebVTT (.vtt) closed caption/subtitle files to videos

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Description

Provide users the option to add a .vtt closed caption file to videos.

This is an important accessibility feature for the deaf or hard of hearing.

Use-case

Things to consider:

• Whether more than one vtt file can ever be added to a single video.
• Whether we distinguish between the kinds of WebVTTs: captions or subtitles. Default appears to be subtitles.
• How the labels for the individual track(s) are to be determined. For example, one possibility is choosing a language that will in turn determine both the label and srclang of the track.
• Whether to bother checking & honoring streams containing an mov_text tag in mp4 containers
• Sanity and security checks. eg size limits.

I personally would also like to avoid solely relying on third-party automated caption generation as the only solution.

Acknowledgements

Yes

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I would like to respectfully request an Accessibility label to mark issues like this and to help us make a more marked distinction between Accessibility and Enhancement please.