How Rovio Robot orientation works?

Hello everybody,
Can somebody me explain how it works? ROVIO TrueTrack Overview - YouTube
I mean this magic light that shines on the ceiling.. And how robot knows where it is now?

My guess would be that it's similar to the orientation sensor on the Wii remote. That sensor uses a 'camera' which reports the position of the brightest IR spots. If those spots are in a known position relative to the docking station the Rovio will have an absolute coordinate system relative to the docking station. As additional spots are added the absolute coordinate system can be extended. If the sensor looses sight of all the spots it has to use dead reckoning.

http://wiibrew.org/wiki/Wiimote#IR_Camera

Yes your are right it must work with "cam". It is crazy what is possible those days..