Originally Posted by Dirty Dane

Examples:

Forum:
I noticed on a porn piracy forum that a filehost was personally advertising their service. "Upload to us, and we pay you X per Y downloads". The thread was even sticky. At their website, however, their TOS said something like "do not upload without authorization, blah blah...". It's quite clear that such statement is only for cosmetic and legal protection. But the thread is evidence of encouraging piracy, also the context since it was only pirated files linked on the forum.

Tube:
"Upload to us, become a porn pimp/king". While that slogan and other "prizes" is not directly commercial, it still encourage and motives the uploaders to get a "name", just like the torrent sites or newsgroups. If additionally the tube uploads are to be approved before published and there are tons of full movies from different sources with same uploader, the chances of piracy (and the hosts knowledge of it) is close to 100% in most cases.

Torrent sites (and some tubes):
"You are not allowed to upload for commercial purpose. We delete "spam" ". That statement alone leave out anything else than piracy. Well, maybe 0.01% of the porn uploaded is someone made themselves...