The file is muxed, the audio and video are on the same track. QuickTime only sees a video track and an audio track and since there both on the same Qt only grabs the video, I suggest looking for other apps to convert the video their might be one that supports muxed videos. If it's just one video you can send it to me (Benjamindaines @ gmail . com) and I'll un-mux it as soon as I can.