need webcam software for motion sensitive recording

[ultrachrome]

I have two cats and one or both are misbehaving so I've setup a camera to surveil the scene of the recurring crime.

I'm looking for software that will record video just when there is motion to conserve disk space and allow efficient review.

The software I have now records a video of user defined length each time there is activity in frame. However, this ends up producing several video segments and most of them miss the action.

What I'm looking for is software that will record one long video comprised only of motion in the frame. When the frame stops changing it should pause recording. An old colleague once demonstrated this on linux but I'm looking for something to run on XP.