private function frame(event:Event):void {
  var h:Number = systemManager.stage.height;
  var w:Number = systemManager.stage.width;
  var dx:Number = Math.random() * 2 - 1;
  var dy:Number = Math.random() * 2 - 1 ;
  vx += dx; vy += dy;
  var s:Number = w/800;
                            ball.scaleX = w/800;
                            ball.scaleY = h/600;
                            vy += gravity;
                            ball.x += vx;
                            ball.y += vy;
                            var left:Number = 0;
                            var right:Number = myVid.width;
                            var top:Number = 0;
                            var bottom:Number = myVid.height;
                            
                            if(ball.x + radius > right)
                            {
                                    ball.x = right - radius;
                                    vx *= bounce;
                            }
                            else if(ball.x - radius < left)
                            {
                                    ball.x = left + radius;
                                    vx *= bounce;
                            }
                            if(ball.y + radius > bottom)
                            {
                                    ball.y = bottom - radius;
                                    vy *= bounce;
                            }
                            else if(ball.y - radius < top)
                            {
                                    ball.y = top + radius;
                                    vy *= bounce;
                            }
                    // myVid.mask = ball;
                    }