South Korean and some Scandinavian cities are the only residential broadband last mile networks capable of transmitting (as in streaming) any HD movie over the net. Americans and the rest of the world have to download it first.
The layout of last mile broadband capable of this in the US is a niche super-high-end developer market, catered to by miniscule niche players like Eagle Broadband Inc.
We're talking ~5GB of data for each hour of HD-DVD video, and ~5GB for each 45 minutes of Blu video. That is a longer time then driving to Blockbuster and much longer than video on demand. The Lord of the Rings Trilogy HD-DVD would fill the Mac Mini's harddrive.
Apple would need to develop a proprietary distributed media network like Valve's Steam to make it work.
Possible. One heck of a project, and one where Walmart Blockbuster and Netflix are already investing.
It will come down to the film studio's anti-piracy lobbyists and lawyers.