I don't know if this answers your question, but I did a quick search on supported file formats.
Another S.O. Answer:
Supported Formats This class supports any movie or audio files that already play correctly on an iPod or iPhone. This includes both streamed content and fixed-length files. For movie files, this typically means files with the extensions .mov, .mp4,.mpv, and .3gp and using one of the following compression standards: 1. H.264 Baseline Profile Level 3.0 video, up to 640 x 480 at 30 fps. (The Baseline profile does not support B frames.) 2. MPEG-4 Part 2 video (Simple Profile) If you use this class to play audio files, it displays a white screen with a QuickTime logo while the audio plays. For audio files, this class supports AAC-LC audio at up to 48 kHz, and MP3 (MPEG-1 Audio Layer 3) up to 48 kHz, stereo audio.
So that would be my guess why :) Coulndt you just convert to MOV ?
Edit: Link to SO answer where quote is taken from: Link