Experience already tells me the answer is 'yes', but I'm curious if anyone has a reference.
Recently, my cable internet went out. I think: no problem, I've got all kinds of purchased movies and TV shows already downloaded, so I'll watch them until the internet comes back!
I can see the library from my (3rd gen) Apple TV, and choose an episode, but when I try to play it, I get the loading spinner. It just hangs until the screensaver comes up.
Meanwhile, I am able to play (DRM-free) music over AirPlay from the library. And Home Sharing appears to be fully authorized--I can control the Apple TV from my phone, I can see the full iTunes library, etc.
Can it be that the Apple TV is trying to phone home every time I play I locally-downloaded, purchased item?