I mean... Yes, I don't doubt there is some on there, it's an unfortunate reality that even with the best moderation in the world, you can't catch all the henious shit.
But... 20,000 videos worth like the article implies? I mean I can promise it's not literally that many because because several of the vids being discussed here are of me and those were all extremely consensual (and I think are all faked). And I have a lot of friends who do similar content whose stuff winds up on those sites - it's a super popular fetish.