I had great difficulty creating a good screencast for the previous blog post. Various tools I tried all had horrible flicker problems in the captured video. I think the problem is related to the GNOME compositing window manager I'm using in Fedora 18. After various tools failed, I solved the problem using vncserver to set up a separate X11 display in which to run the demo app, and using ffmpeg to record the video like so:
ffmpeg -f x11grab -s 1024x768 -i eternity:2 capture.webm
(where 'eternity:2' is the DISPLAY for the vncserver)
Update: Ignore the above solution. Andrew Overholt pointed out that GNOME Shell has screen-casting built in: just press Ctrl-Alt-Shift-R to start and stop, and .webm files are dumped in your Videos directory. It works perfectly for me! Somehow in all my Internet searching I never discovered this feature.