MP4Cam2AVI is a freeware app for digital MPEG4/MJPEG cameras.
It converts and joins mp4(mov) files to avi without video recompression (performs direct stream copy conversion) - video quality is not affected.
It should work with .mp4 and .mov files with MPEG-4 Advanced Simple Profile or MJPEG video, and AAC LC, u-Law or PCM sound, i.e. with mp4 or mov files from all current MPEG-4 cameras (Sanyo Xacti C1/C4, Olympus C770 Movie, Pentax Option MX/MX4, Sony M1, etc.) and photo cameras with .mov video.

Program is freeware (GPL):
http://sourceforge.net/projects/mp4cam2avi/

Homepage:
http://mp4cam2avi.sourceforge.net