function _detectVideoSignal(video){
		var canvas = document.createElement('canvas'), ctx, res = false;
		try {
			ctx = canvas.getContext('2d');
			ctx.drawImage(video, 0, 0, 1, 1);
			res = ctx.getImageData(0, 0, 1, 1).data[4] != 255;
		}
		catch( e ){}
		return	res;
	}
@private
@param	{HTMLVideoElement} video
@return	{Boolean}