The two-screen TV user-interface can display a Screen Select button on the mobile device's touchscreen.  The Screen Select button enables viewers to watch video on the screen of their choice — including the smartphone screen or the screen of any connected TV in the viewer’s home.  Viewers can even switch screens in the middle of a video.  For example, a viewer can transfer a video from the living room TV to the bedroom TV in the middle of a movie.

The Screen Select button pull-down menu shows all available screens.
By always displaying the user interface on the mobile device, it is possible and easy to play TV programs on any screen in the house while maintaining the familiarity and consistency of a single user interface.