[makeitdouble]

I'd assume them being very cooperative with rights holders makes it a lot more difficult for other companies to enter the market and disrupt them.

If tomorrow you come with an alternative that pleases customers but irks IP lobbies, you'll be fighting that battle alone while Youtube continues business as usual. Today the only alternative is pirating related, and it is notoriously a tough business model now that financial system players can just cut offending companies off their network.