I too have this exact problem. I have reported a couple of movie purchases as problems to itunes store but they cannot seem to fix the error.
When I purchased 3 films this week from the store from my iPad2 they worked fine and even played through AirPlay using my Apple TV, but as soon as I connected my iPad to my MAC OS X ML to update and sync, the films deleted themselves from my iPad and then I couldn't get them back on and cannot play them from iTunes library.
Error message appears as "This movie requires QuickTime, which is not supported by this version of iTunes."
I've tried reinstalling iTunes completely and even rolling back to version 10 which wouldn't work properly. I've tried to install updates for QuickTime but the website won't let me install a version i already have and MAC doesn't seem to have a very intuitive program removal tool like Windows does. I've tried re-downloading from the store to no avail....this is my next step to find out from iTunes on a forum...what the hells going on with version 11 Apple...????
@ phyllisfromgalloway, did not work for me! now it says "iTunes requires 64 bit, to start in 64 bit mode, uncheck box...." any other ideas anyone or do we need to wait until Steve steps in from beyond the grave...? So this is official? Apple released an iTunes , which does not support QuickTime, one of THE Apple innovations????? Thats sad.