The Future is Now!
My Roku stick already does that; you hit pause on any one of the apps being serviced by Roku, and a silent, still ad (or promo) pops up on the screen. Now, it is not clear whether that is coming from Roku or from the actual streaming app I'm running via the stick, although since the format of these ads is different (full screen, half screen, half screen with alpha channel gradient to allow you to see the actual paused source underneath) would lend one to believe that the app itself is foisting the ad upon us wearied viewers.
Now if this is indeed the case, and Roku starts overwriting the app's ads with its own, I'm not real sure that the app folks are going to take too kindly to Roku usurping their ha'pennies in revenue.
This could get interesting. Do I smell popcorn?