You can't put ads on YouTube, AdSense is already there. But you can blog videos and run the ads on your blog. Going further you can do mash-up site like GooTube is. But you allways could, no matter of the deal
www.infectiousvideos.com has revenue share for videos... not sure about the legitimacy - but really these sorts of sites are just specialised blogs so if they aren't allowed I can't see how myspace would be allowed to do embedding. I haven't seen one of these sites hit critical mass though... i'm surprised more people aren't jumping on the revenue share model.