Airplay downloaded content from devices to Apple TV over a wireless network with no internet access

I tried chatting with Apple's support team and they couldn't figure out what I was asking, so I thought I would try it on their forums.

I am setting up an Apple TV to simply be used for mirroring to a projector in a building with no internet access. I have a router setup for creating a local wireless network. I can easily mirror my iPhone to the Apple TV, but the second I try to mirror a downloaded movie on my iPhone to the Apple TV, it sits their with a buffering symbol and comes back with "Can't play this right now. Unsupported video format." The kicker is the second I connect the Apple TV and iPhone to a network that does have internet access and mirror the exact same downloaded content, it works fine.

My question is, can you play downloaded content to an iPhone/iPad/Mac through an Apple TV over a wireless LAN that does not have an internet (WAN) connection? It would appear that even though its downloaded content, the Apple TV is still doing some license check or something before playing the content, which is slightly pointless since you then can't ever truly play downloaded content while offline in this specific situation.