Gilbert and Frank welcome returning guests Dick Cavett and author-producer Robert Bader for a look back at Groucho Marx’s memorable appearances on “The Dick Cavett Show” and a look ahead at the new Bader-directed HBO documentary, “Ali & Cavett: The Tale of the Tapes.” Also, Johnny Carson disses Jerry Lewis, Zeppo misses Chico’s wedding, Cary Grant romances Amelia Earhart and Danny Kaye zings the Duchess of Windsor. PLUS: Orson Welles meets the Fuhrer! The lost novel of Truman Capote! The triumphant return of Richard Loo! James Mason stars in “The Honeymooners”! And Dick reflects on his friendship with “The Greatest”!