The `sort' example will break past one-digit numbers without the -n flag, and the example for `uniq' isn't even accurate without sorting first (not to mention the UUOC).<p>Setting aside the errors, the author recommends `xdotool' for finding screen coordinates for ffmpeg, but `slop -f %g' allows you to click and drag to select a rectangle and outputs a geometry string that can be given directly to ffmpeg, which is a lot faster.