A lot of these site (like RedTube and such) originally just posted videos and straight up violated copyright claims until they got DMCA takedowns. Eventually th

A lot of these site (like RedTube and such) originally just posted videos and straight up violated copyright claims until they got DMCA takedowns. Eventually they started workout out deals with the studio for low-quality version and clips, sharing revenue for people who clicked through to buy full or HD versions. Then eventually the big studios just started buying the toob sites and cut out the middle. Most of them serve a subset of studio content or clips. Tumblr's limited video size/length really helped contribute to this model. Most people watch the clips, but the people who buy can get sucked into a lot of hidden subscriptions they forget to uncheck, or even direct up-selling they'll intentionally select.