Development Flash ActionScript

package
{
    import flash.display.Sprite;
    import flash.media.Video;
    import flash.media.Camera;
    import flash.events.Event;
    import flash.events.ActivityEvent;
    import flash.text.TextField;
    public class Main extends Sprite
    {
        private var cam:Camera;
        private var vid:Video;
        private var hasCamera:Boolean = true;
        private var text:TextField;
        public function Main ()
        {
            cam = flash.media.Camera.getCamera();
            vid = new Video();
            vid.attachCamera(cam);
            addChild(vid);
            cam.setMotionLevel(20);
            this.addEventListener("enterFrame", enterFrame);
            cam.addEventListener(ActivityEvent.ACTIVITY, active);
            text = new TextField();
            addChild(text);
            text.x = 300;
        }
        private function active(evt:ActivityEvent):void
        {
            trace(cam.activityLevel + " " + cam.motionLevel + " " + cam.name);
        }
        private function enterFrame(event:Event):void
        {
            if(cam.activityLevel < 10)
            {
                text.text = "No activity detected";
            }
            if(cam.activityLevel > 12)
            {
                text.text = "Motion!";
            }
        }
    }
}