If you want to be geeky, try ffmpeg. Here is the code
ffmpeg -f x11grab -s 1024x768 -r 25 -b 1000 -g 300 -i :0.0 -qmin 2 -qmax 5 outout.mpg
is the frame rate, 25 to 29 is good enough
is the screen resolution to capture. In this example the entire desktop is captured. To get the screen size type xwininfo and then click on the desktop. In the output, the last line -geometry is where the screen resolution is.
If you wish to capture audio with the screen capture, type this
ffmpeg -f x11grab -s 1024x768 -r 25 -b 1000 -g 300 -i :0.0 -qmin 2 -qmax 5 -f oss -i /dev/dsp output.mpg
Hope this helps.