I’m not that familiar with the speedrun community, but no way they do much checking for any runs that aren’t reasonably in contention for a top spot right?
I used to be a speedrun verifier for Portal a while ago and in general we'll reject anything that looks like very little effort was put in it. For Portal this would be runs somewhere above the hour mark, but obviously this varies for other speedrun communities which I can't speak for. For actual runs though it's common to watch them on 5x speed or faster as it's still relatively easy to catch someone breaking the rules at that speed. It also drastically speeds up the time it takes a run to get verified for such a popular game with a limited amount of volunteer verifiers.
I was the first person to do a 25x Inbounds run and I felt bad that someone had to verify it. It took like 6 hours with multiple instances, though, I doubt they actually kept track of the whole thing lol
Some of the more competitive games don't even demand that you submit a video of your run if you aren't in contention for the top 10. Some games you can just "claim" a time and you'll be added to the leaderboard.
Depends on the game/community I think. There’s probably common tells for different games - eg if it’s obvious someone picked a good seed for Minecraft. Probably don’t have to watch the whole video, just skip to a few critical points.
If you take the meme at face value, sure. I'm sure they have to validate some runs, I'm also pretty sure they don't extend that policy to 2500 spots down the list.
Most runs in general do not get scrutinized unless something about the submission is suspicious in itself. The community is very tight knit and there is nothing to gain from being on the leaderboard but clout.