video update(s) / handler
Handler for when the video frame updates. This draws the current video frame into the bitmap data and applies an image effect.
parameter: event Event dispatched by VideoLoader. 

  
                  private function onVideoRender(event:Event):void {
                          var bitmapData:BitmapData = new BitmapData(_video.width, _video.height);
                          // draws video frame into bitmap data, making sure it is at proper scale
                          var matrix:Matrix = new Matrix();
                          matrix.scale(_video.scaleX, _video.scaleY);
                          bitmapData.draw(_video, matrix);
                          // isolates color in copied data
                          _shaderEffect.apply(bitmapData);
                          _filteredScreen.bitmapData = bitmapData;
                          // updates flame image
                          drawFlame();
                  }