I've only played MP4 files but those were created from 720p recordings. The 720p recordings were done with an Hauppauge HD-PVR which uses the so-called analog hole to record HD from cable/satellite set top boxes. The HD-PVR uses hardware encoding to put the video in a H.264 container. I converted that file to MP4 to reduce the file size but haven't tried to play the original H.264 file on the Edge. The MP4 files played great.
You make it, we break it.