I was kinda wondering too, and did a (very shallow) dive into the JavaScript on that page. I'm almost positive they are using Deepgram(dot com)'s speech-to-text service.
I ran whisper.cpp on that audio file on my laptop, and it does a reasonably well job too.
justinclift|1 year ago
deskr|1 year ago
iv42|1 year ago
cb33|1 year ago
https://syntax.fm/621?t=0:23:15