Got my invite to Joost (I meant Hulu ;)) this afternoon and I can only say that this will (make that still can) be a massive supernova success. Think completely accessible, free and remote VOD. With the integration of standard ads (pre-roll) to premium content from the likes of MTV and Comedy Central, there's little to no reason why content providers wouldn't openly participate (least none that I can think of). There are hiccups in the service - video play can get a bit staccato, you need to scroll through a lot of content - but the beta is really impressive. The ability to stream full shows via P2P, combined with an attractive, stupid simple interface will make this super viral once officially launched.
With two kids in the house, the wife and I use Comcast on Demand a ton in the house (Dora the Explorer on demand is a parent's best friend). With a few more premium shows (Thomas the Tank!, Bob the Builder, you know the good stuff), Joost will be a constant in my home/laptop, and I get the feeling in millions of others as well. And no, I'm not getting paid for this post :)
P.S. - Hulu essentially upended Joost on content and ease of use (browser access). So just replace all the Joost comments above with Hulu and I can retain a little dignity :)