I attempted to use CBS on Demand to download Survivor. It sucked. Their server kept timing out. Granted, we occasionally have connection issues on our side, too, but a downloaded content service needs to account for that. I didn’t even get the chance to determine if their “24 hour rental” DRM was annoying, since I could never get the damn show onto my computer. They do *not* give refunds for connection issues, despite full-on admitting that they were having server problems with Survivor due to high traffic. And, once you navigate away from the download page, you can never get your license to work again.
iTunes is going to kick their ass in this area if they don’t get their technical crap together. I ended up going to BitTorrent and downloading a questionably illegal copy. Questionably both because it is a free broadcast and because I did pay $1.99 to CBS.