How To Join AVI Files Without Reencoding Them? I have several avi-containers with exactly same type of content, framerate, bitrate and encoding match as they are coming from a camera that splitted the files.
Currently I'm using D-Vision but its development stopped and starting with Lion it tends to break the files which then have to be remuxed to fastforward properly.

Do you have any software recommendations for me? It MUST NOT reencode the streams!
I'm not sure if I get 100% what you want, so correct me if I'm wrong...

You can just use QuickTime (7 Pro or X -> I'm not sure about QT X). Just copy/paste the several files in one new window and export to .avi. It takes some time to export them, but you are not re-encoding them... 

EDIT:
Try downloading this plugin for playing Xvid-files with QuickTime.