Mirror's Edge easter egg revealed!!!

Credit to tuppusolider as he's the person that reveal the glitch:
Quote from Youtube:
"I finaly found the big rat easter egg in mirror's edge!
When i first time heard about big rat easter egg i tried to look if someone was already found it but no, so i think im first one to find this.

This is in chapter 8 when you have to snipe the convoy.
First: shoot the van soon as you see it.
Second: look littlebit up and you see somekind of ad with 9 circles, shoot the middle one.
Third: Enjoy the Rat! =P
UPDATE: You dont need to shoot the circle before van crashes but you still need to shoot the van first and you CAN'T kill the rat. "

Want to see? Just go to http://www.youtube.com/watch?v=TtaIzSmhuls