I would just throw into the ring that appleTV was working fine until I pulled the plug out to put it in a different socket, i.e. rebooted it. This would appear to be a theme.
The same thing happened to me, since I specifically rebooted my tv just to test this very issue.
I'm guessing part of it is that the tv probably doesn't check the iTunes site very often... Probably on a scheduled basis to refresh its cache. So, once it's had a successful refresh, it probably doesn't reschedule the next check for at least a few hours. Rebooting it, of course, would likely cause it to start the refresh cycle all over again.
Winston where is this youtube pluggin you mention? I am not missing features am I?
The official YouTube plug-in was announced by Steve Jobs today, but is not going to be released until mid-June. It will likely come as an tv software update, through the Settings menu.
There
is a YouTube hack available already, but it requires manual modification of your tv, which will void your warranty.
If you have any apple store purchased media, it won't work without the default route set up properly. (found this out tonight). Guess ATV doesn't use the library to check authorization...
Oddly, I'm not having this problem... I suspect that the tv may need to check and/or download its authorization keys at initial startup perhaps, and if it's
never been able to do this, then I could see that happening.
All of my own purchased content is playing fine, however, regardless of whether the tv has no default route, or even if I have no Internet connectivity
at all.