In the video below, the iconoclastic singer-comedienne Carol Channing delivers two songs from “Gentlemen Prefer Blondes.” She’s playing Lorelei, a role she originated on Broadway. Darryl Zanuck, the studio head of 20th Century Fox studio, did not engage Ms. Channing for the 1952 movie. The plum role went instead to you-know-who — a huge gamble ...