So which Imagination Technologies VXD is in the 5s? I have never seen this detail published anywhere... A list has been started for previous iPhones here:
Their newer ones support HEVC/H.265 decoding!
Another secret sauce to ATV's usefulness is the Media Center and ClickToPlugin Safari Extensions which both add "Send via AirPlay" for videos on YouTube and other places right to ATV@!
Why Apple does not better integrate AirPlay across the Mac applications I will never know! :(