Merging wmv files and repairing avi files

[ZF]

mencoder -ovc copy -oac copy file1.wmv file2.wmv.... -o file.wmv

mencoder -forceidx -ovc copy -oac copy file1.avi -o file.avi

To install avimerge:
sudo apt-get install transcode
sudo apt-get install transcode-utils

avimerge -i part1.avi part2.avi -o joinedfile.avi