This question might hav been asked in the forum somewhere so pls forgive me for asking it again.

I was looking at the VR display video clip by Johnny Lee, I'm just curious why/how does another wii remote shoot the target when then sensor bar is behind? What IR is the wii remote (which johnny lee is holding) is sensing? I'm really confused.

Wii_remote is infact the sensing device and the senor bar is nothing but just  some IR-Emitting LEDs which are mounted on the glass he is wearing (in the demo). There, he has changed the position of the sensor and sensing device meaning that the second(wii-renmote) is hold still in front of the screen and the first (sensors) are on his head.
Doing so , he can find an approximate estimate of the head position in relavtie to the TV-Screen which will be used in his engine for VR-displays...