Why would an admin run a server if they might have the feds knocking at their door? Sure, people might run nodes that host only their content, but they sure are disincentivized from running any sort of shared service.
This is the same problem as TOR exit nodes and why 3 letter agencies run most of them.
Maybe the live where the feds can't get them?
it's a safe harbor. If the admin unlists videos when they get a DMCA takedown they are in the green.
believe it or not, YT too gets a crapload of copyrighted content uploaded hourly yet they exist
This is the same problem as why an admin would run a forum if the feds might knock at the door, or why an admin would run a website about cats if the feds might knock at the door. It's an overblown fear.