As an update, I have been through 7 or 8 hours now of troubleshooting, loosely guided by Apple itunes support in trying to rent a movie through the Apple TV three separate times, each time being unsuccessful. I have tried:
updating the software on the Apple TV2 (was and is current)
reset it several times
disabled firewall completely
changing DNS servers
switching video resolution
paying more to my ISP for high bandwidth on ADSL
results: loading...or ready in 1 minute (lies)....or play 10 minutes and then "loading, ready in 220 minutes" (lies) - after several hours we just give up and turn it off and use Netflix. Only problem is in Canada Netflix is about 5 years behind on "New Releases".
I have worked in IT for over 20 years so I can actually understand what I am doing, and have NO problems with other services, running 6 PC's / laptops in my house simultaneously, and can run Netflix on two at the same time. ALL other aspects of my various Apple hardware work fine. As I have told itunes support, this rental feature is garbage - the problem is them. Whoever manages the AppleTV area should be replaced by someone with the kahunas to actually resolve this issue or announce a plan to resolve the issue. Way too many people with the same problem. If it doesn't work, quit advertising it and take it out instead of stealing our money for rentals. I tried 3 times - and tried to work with the company to resolve this - only to come away angrier than ever. Off to a different product now, like thousands of other people I would expect.
Frankly, reading through the various online blogs and support areas - I wonder if this HD rental service works at all on AppleTV's, or if it is just taking money away from people who believe they bought a product that will allow them to rent movies. Screams "Class Action Lawsuit" if you ask me.