I have an iPhone 5s with the Apple Lightning > HDMI adapter. The streaming game video goes almost full screen on my 720p plasma TV, but there's a narrow black border around the edges. It's even worse on my iPad 3 - I get video centered in an approx 4:3 box, and the left/right sides are chopped off. If I select full-screen in the iPad app, the video portion shrinks to a smallish box in the middle of the screen, with lots of black area on all 4 sides.
The native Apple video player app can fill the TV screen completely, edge-to-edge. Why can't the NFLST app do this?