Someone commenting on that video suggested an app or more that requires permissions that ultimately is exploited or intended for this purpose. I don’t like it, whatever it is. For your hack scenario is that a few kids with too much time on their hands or something a little more advanced or official? I hear creepy things about Google but I did NOT hear that this scenario was “android only.”
Yeah a shared app exploit would be an easy door for such a hack but who knows what way someone figured out how to do this. Could even be a secret embedded command only known to a select few developers and gov agents. It would be useful to thwart terrorists in an emergency situation, but would need to be kept secret for as long as possible to prevent contingencies of course.