$.extend({
jYoutube: 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 "http://img.youtube.com/vi/"+vid+"/2.jpg";     
    }else {       
      return "http://img.youtube.com/vi/"+vid+"/0.jpg";     
      }   
 } });