As much as I like iTunes, it sucks that you cannot just stream your movies to your mobile devices, and you cannot stream movies over cellular too. While most Apple users are only having 16GB how in the world you're going to fit those movies. Some of us already ditched our home internet and no way I can watch any of my movies if they're not available on my computer. AppleTV cannot even store those movie. This is really a good excuse not to deal with Apple services sometimes.
You can stream iTunes Movies to mobile devices and, if you flip the switch in the TV app settings, you can stream over cellular too.