A new Apple Support article has been posted noting that iTunes 10.4 users on OS X Lion may encounter problems opening older media files with an error message that “This movie requires QuickTime, which is not supported by this version of iTunes.” The article explains that some older media files may still require QuickTime in order to play and that QuickTime only runs in 32-bit mode.
In order to play media files that are affected by this issue the article provides instructions on how to explicitly open iTunes in 32-bit mode.
Notably, this issue only affects OS X Lion users as iTunes 10.4 continues to run in 32-bit mode on older versions of OS X.