$.extend({
  youtube: {
		thumbnail: function(url, size) {
			if (url === null)
				return '';
			
			size = (size === null) ? 'big' : size;
			
			var vid;
			var results;
			
			results = url.match("[\\?&]v=([^&#]*)");
	
			vid = (results === null) ? url : results[1];
	
			if (size == 'small')
				return 'https://img.youtube.com/vi/' + vid + '/2.jpg';
			else 
				return 'https://img.youtube.com/vi/' + vid + '/0.jpg';
		}
	}
});