what do ya'll think about the vendetta bow mounted rangefinder?

have ya'll seen this thing? my question is how do you know if it is ranging what you are targeting? it looks awesome have any of you tried this yet?

 

I think it's a cool idea. I'm just waitin for all of the Nancys that complain about a 4.5 lb bow vs a 3.8 pb bow to say they love it.