I saw those for the first time yesterday. Apparently some asshat has a patent on displaying an interstitial when the mouse moves above a certain x coordinate dressed up as "measuring exit intent"
In this case it was BounceExchange, but others like Exit Monitor & Picreel do the same thing. Its popular on e-commerce sites where you have a funnel for converting vistors to paid customers.
They have a patent on moving the mouse cursor towards the address bar?!.