How do video sites stay alive?

There used to be a time when video sites would shut down due to high traffic and bandwith costs.  So how can sites that promote downloading videos for free stay alive?  I'm talking about short clips, funny videos, etc.

The kind of person that uses ad blocking is the kind of person that habitually ignores adverts anyway. Blocking is actually saving them the bandwidth of sending you the image or Flash file in the first place.