Want to be invisible when you walk past a security camera? Here's how:
This is a page that i machine-translated from German, so it is a little rough. But as soon as you see the idea it is blindingly obvious how this works. You start with some infrared LEDs (like the ones you would find in a TV remote). You power them up. And you wear them somewhere near your face.
See this article for ideas on how to create your own infrared LED array:
It would work just as well to use an LED flashlight (or any bright flashlight fo that matter), but then everyone around you would look at you funny. Since infrared light is invisible to people (but not to security cameras), you can wear the device without drawing any attention to yourself from those around you.