function ModifyText ()
{
  if (YD.hasClass(document.body, "gallery_4821790")) 
  {
    var objElement = YD.get("comment")
    if (objElement != null) 
    {
      var str = new String(objElement.innerHTML);
      str = str.replace(/\gallery/gi, 'guestbook');
      objElement.innerHTML = str;
    }
  }
}

YE.onAvailable("comment", ModifyText);