I downloaded Twilight in HD, with the intent of streaming it to the Apple TV. No dice; all I get is a white screen with no audio. It plays fine in iTunes on my Mac. It also will not play on one of the other shared Macs in the house.
Yes. I am able to stream other movies from my Mac to the AppleTV and to the shared Mac in question. I didn't know if it being HD had anything to do with it?