IBM Watson, Google, Azure, and AWS all have speech-to-text APIs. IBM's claims to distinguish between different voices, although when I used it a couple of years

IBM Watson, Google, Azure, and AWS all have speech-to-text APIs. IBM's claims to distinguish between different voices, although when I used it a couple of years ago for Japanese it was a little lackluster. It's pretty inexpensive: IBM gives you 500 minutes free per month and is a few cents / minute thereafter; Google you gives 60 minutes free, and it's 4c/min thereafter. It's an API rather than a service, so you'd have to write a client to use it. IBM's API (and maybe the others) allows you to request time stamps on the output, so you could let people click on your transcription and seek directly to the part of the video they are interested in. I suppose you could always do it on your own machine with Sphinx, too, although I don't know how they compare to the others in accuracy.