Handheld.PlayFullScreenMovie Close Scene

I'm struggling on this bug. Handheld.PlayFullScreenMovie video playing but my scenario is an android while playing that video hit android bak button that scene was navigate to another scene but here not working video only closed and its maintain same scene.

  public void playVideo() {
   Handheld.PlayFullScreenMovie(videoName[randomValue], Color.black, FullScreenMovieControlMode.Hidden, FullScreenMovieScalingMode.Fill);
         }

 public void Update() {
 Application.LoadLevel("MainScene");
 }