If you ever want to embed a video file in a PowerPoint presentation, the following command can be useful. It allows you to convert a video file to wmv.

The wmv format is better supported for playback within PowerPoint (at least on Windows systems). mencoder luckily makes this very easy to do:

mencoder input.avi -o output.wmv -ovc lavc -lavcopts vcodec=wmv2 -oac copy

similarly for mpeg files:

mencoder input.mpeg -o output.wmv -ovc lavc -lavcopts vcodec=wmv2 -oac lavc -lavcopts acodec=wmav2 -of lavf

To create an older wmv version, use wmv instead of wmv2 as the vcodec.