Article:
  Making Screen-Capture Movies
Subject:   ffmpeg can also grab the screen
Date:   2007-08-11 20:54:00
From:   AndresVia


As of version 3 (2007-AGO-01) ffmpeg can grab from X11.


From the man page:


ffmpeg -f x11grab -s cif -i :0.0 /tmp/out.mpg


Which is a *lot* easier.