But, well, have these companies figured that if people see video clips they like on YouTube... they'll be heading over to the company's official material to see what else is there that might be fun? No, they have blinders on; they only see the other side:
Viacom’s suit acknowledges the value of its programming to YouTube, noting that its content “acts as a substantial draw, attracting users to the website.”
It does work both ways. It's free publicity, folks.