I found two links
http://www.joost.com/presents/indycar-series/
https://joost.com/presents/mos/
I found other similar links, but some say "We are sorry, but there are no invitations left" when you click on the link, so these two links might eventually say that.
Though now I'm completely confused because I just went to
www.joost.com and it had a link to click on to try it and it says this on the next page:
"Joost beta will soon be available for you to download. If you want to be one of the first to try out Joost, fill in the form below - we'll invite you as soon as it's ready."
When I went on the page yesterday or the day before it said I had to be invited by someone else.
Who knows.
Well we'll see if I get an invite.
Update:
I ended up using my wife's email on the indycar link and got an invite.
I downloaded it.... so far it seems to be a resource hog. I'm also having trouble switching back to it after switching to this window, but I hear the tv show I was watching "News radio" in the background... It seems to be working better now.
I have a gig of ram but it mentioned on install that it recommends something like 48mb of video ram and I only have 38mb, but that I should still try it.
Anyway, I no longer need an invite, but maybe able to send them at some point if the links above don't work for you.
Another update:
I finally got a chance to try it out. Yesterday I only saw one channel apparently. I actually found this one sci-fi show Time Trax. I had seen an episode or two back in the day but never see it on tv.... after watching the beginning of the first episode, I might know why its not on tv much

J/k . Its worth a try if you like to play around with that kinda stuff. Just close it down in the tray icon when you are done because it uses a lot of bandwidth apparently.