@jellyroll:
I have no idea how to do that with gtk-recordmydesktop, because its behavior seems odd to me.

But according to the ffmpeg wiki [1] (and some playing with options on my side) this should produce a more or less acceptable fullscreen video (without sound) of your N900 screen:I found my N900 (overclocked to 850MHz) can't actually cast a video above 5 fps and creating an avi seems to result in a better video quality than flv.
I'm no ffmpeg/libav expert though, so someone else might very well come up with a very efficient video codec that produces even better results (no compression at all should be best).

The above command only seems to work with (Easy) Debian's ffmpeg (actually libav) and not with Maemo's, probably due to the latter being to old.
I can also only run it from within an Easy Debian Desktop (but I can record the Maemo desktop as well) and not via debbie, apparently due to a missing $DISPLAY. This should easily be fixed but I'm too tired right now (2 am) to investigate on that.


[1] https://trac.ffmpeg.org/wiki/Capture/Desktop