When 99% of the videos on your site are stolen, it's hard not to
know it.
When you are paying people to upload stolen content, it's hard not to
know it.
When you get hundreds of DMCA notices, it's hard not to
know it.
When you are running video scrappers on legit sites, it's hard not to
know it.
Get my drift.....
Pornographers in the USA have 2257 to contend with and do vet every image on their sites.