They can't mirror automatically - it always appears to the app as a second window. There are games (e.g. The incident) that use this to let you play on a TV, a

They can't mirror automatically - it always appears to the app as a second window. There are games (e.g. The incident) that use this to let you play on a TV, and things like Keynote can display the presentation on the output and presenter notes on the device itself.