Niel : thanks for the advice... but no luck yet. Anyway, it was not an old file but a recent rental.
However, this helpded me partly :
- locate the file in the Finder
- drag it on the desktop to create a backup copy
- delete the file in the iTunes (choose "yes" to erase the physical file if prompted)
- drag and drop the backup copy, like you would import a new movie in itunes
With this, I am able to play the movie in iTunes and on the Apple TV.
Still, cannot transfer it to the iPad.
I am at a loss here...
A point of clarity on this. Ref the files that are not supported, it depends on when they are created not when they are downloaded. I had the same problem last year and the 32 bit fix suggested above worked then and has worked again now.
On 10.8.3 update it seems that the update has overwritten a number of customized settings including the 32 bit itunes change. Ive spent days trying to get it all working as It was prior to the latest update. Apple - the quality of your updates seem to be slipping, come on guys get with the program.
Z - not sure why the fix didn't work for you
Corwin of Amber