Step 3: Test video recoding without sound.
Start up a terminal and type in: The original desktop size we are using is 1024x768, but Youtube only takes 640x480. FFmpeg will do the conversion for us on the fly.
$ ffmpeg -f x11grab -s 1024x768 -r 10 -i :0.0 -s 640x480 -r 10 filename.avi
Press q in that window when you are ready to stop.
Now play it back with your favorite movie player.
See an example: http://www.instructables.com/id/Getting-instructable-counts-continued/