If you have two movie files that need joined and you are wanting to use linux then this might help you.
If the files happen to be avi files then go ahead and use this nifty command
avimerge -o joined_filename.avi -i file1.avi file2.avi file3.avi…
and if they happen to be mpg files go ahead and use this one
mpgtx -j file01.mpg file02.mpg -o joined_filename.mpg
Just thought that I would share that with everyone.