I would like to connect an external HD to Airport Extreme, then stream the movies on that hd to my Apple TV. I understand that iTunes would need to be using the external hd as it source. Would this work? I've heard concern about the bandwidth of the network getting all used up even though I'd be completely on 801.22n. Has any one set up their ATV like this (sort of an alternative to swapping out the HD within the ATV.) Thanks.