I haven't found the perfect method yet, but here are the key problems, and what I'm doing at the moment.

Challenges

• If you use too high a resolution, the viewer won't be able to read the text of the install process
• If you use too low a resolution, aliasing will make the game look bad
• If the game changes video modes, ffmpeg aborts
• If you need to concatenate two video files, you may have to re-encode them into mpeg-1, mpeg-2 DS, or DV before concatenating them (see http://www.ffmpeg.org/faq.html#SEC27 ), which can introduce more compression artifacts.

What I currently do

I use the tips at https://wiki.jasig.org/display/JSG/Screencasting+In+Ubuntu

i.e. his ffmpeg script for recording, and avidemux for editing.