Android Back Button when FLVPlayback component in full screen

I'm launching an FLVPlayback component in to full screen by setting fullScreenTakeOver = true and setting StageDisplayState to FULL_SCREEN in an air for android app. This works fine. The video plays in full screen

But when I press the device Back button, it quits out of the app.

Everywhere else in the app I can catch the key_down event and do preventDefault(), stopImmediatePropogation(), but the event doesn't seem to fire when FLVPlayback is in full screen.

I've tried adding the Key_Down event listener to NativeApplication.nativeApplication, to stage and to the FLVPlayback component itself. None of these seem to work.

I do, however, get the correct behaviour when I test the app in Flash IDEs simulator

Thanks

Ben

EDIT:

Also worth noting. Using latest Flash CC and AIR 17 testing on an S4