Merge AVI-files without recoding in Mac OS X Lion

To make your copy of avidemux2.app work, simply open the application bundle (show package contents in finder) and remove the files libxml.2.dylib and libiconv.2.dylib from the Contents/Resources/lib folder.

This will make avidemux2 use the versions that ship with Lion and which seem to work just fine.

This works for me:

cat part1.avi part2.avi part3.avi > tmp.avi && mencoder -forceidx -oac copy -ovc copy tmp.avi -o output.avi && rm -f tmp.avi

Then output.avi should not only have the whole content but also have the indexes recalculated so the whole movie plays.

Avidemux is an open source tool for editing/combining videos, and there is a Mac port:

http://avidemux.sourceforge.net/