I'm currently making a podcast, and also have a teaser for it. The latter was made with headliner.app. I noticed that I can add a transcript file (if I didn't want it to do it automatically). It mentioned something called VTT or SRT file. So I looked up how to create a SRT file. This page answered my questions and it's pretty straight forward.
Each section is proceeded with a number followed by start and end section followed by the caption you want shown.
1 00:00:03,000 --> 00:00:05,000 Hello, everyone! 2 00:00:05,000 --> 00:00:10,000 More stuff, talking about something, foo bar and so on.
I opened up Quicktime player at the time, and just looked up the times for each section.
Saved it with
.srt and to test it, I opened up VLC, added the video and SRT file and played it, it picked it up! 🙌