Happy Dance!! I purchased a TV Show and it solved everything. I like the product... now, but what a pain all around, with very little direction. Thank goodness for forums like this. What a nice way to outsource your support to you customers! If it helps anyone, this is what I went through to gt everything working across a wireless AirPort Extreme network (iMac source):
1. Followed instruction out of the box, connected to network fine, established connection to iTunes fine, set up sync fine
2. Couldn't play any purchased content on ATV (unauthorized), logged in about 5 times on ATV, which is a PITA, no luck
3. Unplugged ATV, plugged back in, login in was successful
4. White screen on video, couldn't play purchased music
5. Purchased TV episode, everything played fine
Between steps 4 & 5 I also unnecessarily did the following over the course of a day:
1. Reset ATV
2. Reset ATV to factory
3. Removed ATV from iTunes
4. Deauthorized/reauthorized Tunes
5. Changes every video setting thinking that it was my TV, as Apple would never release a buggy product in the market
Anyway, thanks for the hints, as now I'm liking this little piece of gear.