Disney lost their old camera tech used to make a "yellow screen" with sodium vapor lights.
It's actually better than a green screen because the yellow light is so specific that even if you remove that particular frequency of light, everything else still looks fine. You can do all sorts of things that would normally be very difficult to pull off with any of our green screen tech (like drinking water in a clear bottle or wearing a rainbow dress).
As someone who uses Whisper fairly often, it's obvious that they've trained off of a bunch of YouTube videos.
Most of the time it's very accurate, but there have definitely been a few times in long transcription sessions where it will randomly hallucinate that someone is saying "Don't forget to like and subscribe!" When nothing was said anywhere near that.