This is crazy!!! When you take a picture of your sensor bar, there are 5 purple LED lights on each end, that only a camera will pick up!!! FREAKY!!! I discovered this awhile ago, and decided to say something about it.
<sigh>
Both video cameras and pictures do this. If you put a remote up to the camera and press a button, you will see the light inside the black thing.
This is because they are communicating with the sensor using LEDs and some light wave that I can't think of off the top of my head. Infrared maybe.