I'm a totaly new in PD and am trying to build a following system:
1st USB camera is doing motion tracking.
While there is no motion, image from USB camera 2 (which might be or might not be moving) is shown on screen.
When (enough) movement is detected, video (from a file) is played on screen instead.

I feel in PD this should be very easy to make, but since I've only done some programming in traditional languages (basic, some php), I just can't put my grasp on this inlet and outlet thingies.

I managed to switch from one device to another manually, but how to to it automatically trough an "event", I just can't figure out.
I would really appreciate someone leading me trough this example, since I think it's the best way for me to figure out how PD really works.