Screen recording is not niche, anyone who works remotely probably does video calls daily and the others are somewhat more niche but I'd guess that at least 50-70% of people do at least one of these things
(As a side project, I am writting my walyand compositor, and I know that if it supports screen recording, that's going to be something certainly hacky and I can disable at compile time).
I can see a lot of non-techy people not knowing how to do this but among people who know how to do it I bet it’s above 50% who use it