Any half decent paysite has better content and more clear content than a tube. Most tube sites have a raft of decent videos but won't satisfy the surfer forever.
I make sales from
www.wanktube.com and I know many others do from similar tubes which are webmaster friendly and send good traffic. Ratio of 1:300 so far, so yes ... tubes make sales. Of course idiots who upload 20-30 min clips on their tube and then complain of no signups only have themselves to blame.