Resilient tenor Rolando Villazón makes a guest appearance on the TV talent search show “Musical Showstar 2008.” In a serious mood, RV performs “The Impossible Dream,” but then things turn very silly indeed when host Thomas Gottschalk (the Ryan Seacrest of Germany) joins the tenor for a production number from Monty Python’s Spamalot. [kml_flashembed movie=”http://www.youtube.com/v/Xdtfqvj-Gr8″…