There are account penalization i.e. a strike system associated with frequent infringement complaints, and it doesn't take many. While it's certainly the case that copyright holders will simply take over the revenue from unauthorized videos, my expectation is that most of these uploaders are not unwitting anonymous types: they actually represent the company. I had read an article years ago detailing that this can be the case but I can't be arsed to find it right now.

It's not a huge leap when you consider it's also been revealed that a good chunk of torrents at one time had been seeded by IPs belonging to corporates.