> I think what I need to do is define an area of the screen and use an A/D to
> digitize the area, then if movement occurs in that area it would then either
> sound an alarm or perhaps have the ability to "learn" your remote control
> keys for "record" and "stop".  It could then start and stop your VCR for a
> user selectable duration.


This has been done in the past with a simple photo-resistor and
suction-cup arraingement. If the light level changes, the alarm trips.

You might monitor the entire scene, to track daylight and lighting
variations and avoid false triggering