This is sounding like a damaged file. But, just in case:
So I try to open it in iTunes again where I get a "this movie requires QuickTime" error.
Try relaunching iTunes in 32-bit mode first, as per the instructions in the following document:
1) This file was from a movie released last week, so the KB article (which I was already aware of) would not fix the issue, which exhibited itself in files long before Lion came about.
2) This still wouldn't address why the movie isn't streamable, yet still playable in QuickTime.
3) Since the BD combo included no physical copy of the digital copy disc like is the norm, I have no recourse for re-downloading it.