This is not excatly about aeromodelling but I think it is useful. My Sony camera is producing mp4 video file like most of the mobile phone or recent APNs. Unfortunately, as soon as you want to edit the video, Windows Movie Maker is unable to recognize this file format. This is a shame because WMM is a nice software (and freeware) to edit quickly a video, add title, a music, then encode it to the right size and definition.
I found on the net a very useful tool that converts mp4 file into AVI. Its name is mp4cam2avi
They say: MP4Cam2AVI is a MP4/MOV to AVI repackaging tool for digital photo-video cameras, it makes their clips editable in VirtualDub, MovieMaker and other AVI editors. No video recompression, no quality loss, fast operation (5-20x realtime), no quicktime needed.
I tried this tool and it works great !
Hope this help :)