Thank you for seeing our billboard!

Google has announced an eye-counting camera (on the right) that can be used on billboards and other public displays to count eyeballs: Here is an article at EETimes. The product is developed by xuuk inc and costs $999. The company claims that the camera can tell if a person looked at it from as far as 10 meters away. I wonder how long does the person need to look to generate a "Click".