I'm actually kind of pissed on this topic just now.
I thought I had bookmarked the article, but I can't find it, so I'll just have to paraphrase.
Apparently the new thing Hulu and other companies are doing (going to be doing) is only allowing access to the majority of their content if you have an existing cable / satellite subscription that is active.
I'm quiet annoyed by this as I've been direly waiting for streaming to get good enough to cut the ties completely. I've gone numerous periods without cable, but there's always that one thing I can never find that I want to watch.
Streaming has been something of a thorn in the sides of Comcast, Time Werner, DirectTV and other companies for some time now. The notion of a world that doesn't need access to their network terrifies them and they have been doing a lot to attempt to mitigate or even prevent streaming (Hello Comcast and all their attempts to keep streaming off their networks by throttling).
So now we're facing a point where these largely free venues are going to require you to have a subscription again all because the big providers are terrified of losing their market.