[User9812]

http://i.imgur.com/0OXmc9h.png

The blue line is an iPad, the red region is the camera line of sight. On the left, you have no mirror, the camera is looking straight ahead at you. On the right, a mirror is attached, it redirects the camera view down to the playing surface.

[mikeash]

Got it, thanks. Nice diagram. I can't help but think that if the connection between the iPad and the stuff in front of it was made a bit more clear on the site, as you have done, that it would be much easier to understand. Or maybe it's just me.