The -oac copy option tells mencoder to just copy the audio stream
(no reencoding). -ovc copy does the same with the video
stream.
The -idx option asks mencoder to build the index if
none was found. This makes searching inside the video easier.
-o stands for "output" and specifies the output file.
The last few parameters are the input video files.
You can join as many files as you like. This will work for videos of the
same resolution, and using the same codec, but any
video format that mencoder recognizes is fine.
