closed captions for videos?

I use TimelineJS3 within our LMS and stream local videos (MP4) within my timelines (using the Google Sheets template). It works, for the most part, though I had to add my own JS listeners to handle when a user navigates away from these videos, as TimelineJS3 would keep playing them when the user navigated away from them (added to all elements with the "tl-slidenav-content-container" in case you're curious).

Anyway, our institution is going through a proactive accessibility initiative and I need to make these videos accessible. I have captions for them (VTT format), but I have been unable to figure out a way to get TimelineJS3 to use them. Certainly there's no place in the spreadsheet template for this. I've also scoured the TimelineJS website and the issues here, but the accessibility items seem to center on images and the interface, not "local" video content.

So, can someone point me in the direction of how to get TimelineJS3 to use the VTT caption files for the videos? If there's not support for this, I may see if I can modify my existing JS listener add-on to add the appropriate element attribute, but it'd be nice if there was a more supported way to do this.

Thanks!

Start by reviewing how TimelineJS3 handles local MP4 videos and how video fields are represented in the Google Sheets template. Compare that flow with the author's JavaScript listener and VTT caption files; done means a supported way to provide captions for local videos, or clear documentation that identifies the required integration.