To the OP's question:
What happens is that the studio will release a DVD title. People buy the DVD, rip it and upload it to the pirate sites.
The a few weeks later the scenes from that DVD are added to the paysite. But by then the content has already been seen for free by millions of people.
Which is why we don't do DVD's. When I did one, I saw that happen almost instantly.
It wasn't worth it.