Any video that has captions, the author's own or the automatic ones. A YouTube transcript extractor reads a caption track, it cannot invent one. If
Show transcript is missing from the menu and from the description as well, that video has no track and there is nothing to read. The audio then has to be recognized from scratch, and that is a job for
our Windows program that turns local recordings into text, which walks through a folder of .mp4 files in one batch.