You do not wanna use caption file because that's looking for a specific file where time codes, where the captioning comes in, and goes out, is related to an actual piece of script, you don't want that, you want Youtube to do it for you, so you go Transcript file, and this is a beta program, but it works very well, like I said, it's in english, no problem, if you want to you can rename it but we don't care. 