You *could* run into the same problem with a hosting company that Perez ran into with YouTube. They have the power to shut your site down too.
As long as there are multiple hosts competing for your business it's not much of a problem but if there is one company that really gets it right with all the killer frontend/backend apps for web video and everyone migrates there then we're going to have the same power imbalance situation as with youTube.
