allowsAirPlay not showing Air Play button in MPMoviePlayerViewController

Question

I'm using an MPMoviePlayerViewController to play a video. I set the instance's moviePlayer.allowsAirPlay to true as it is false by default. However, the Air Play button never shows up in the player controls. Could I have done something wrong, or are there specific guidelines for Air Play? The videos are 640x480, file types AVFileTypeQuickTimeMovie, .mov extension, H264, and PCM audio.

Does an AirPlay device need to be in the vicinity before the button even shows up? I don't have an airplay device, but am an app developer and want to make sure my users can do so if they have such a device.