I'm already recording from my iSight from a python script using the pyobjc bridge and the QTKit framework.
Which framework/device/... should I use to capture the video of my screen instead of the built-in iSight?
P.S. I'm using Leopard (not Snow Leopard) and thus I don't have the Quicktime X API at my disposal.
OpenGL. There's sample code for this on Apple's developer site (SonOfGrab, IIRC).
As of Lion, you should use AVFoundation to record the screen.