And from what I read in the Agnes Moorehead biography "I Love The Illusion", she really didn't want to take the part of Endora. She thought it would never sell, so she decided to do the pilot. It's true, she was shopping in Bloomingdales when Elizabeth approached her do to the part "of the mother of a witch in a new television program". Elizabeth had only met Agnes one or two times before this, through he father, Robert Montgomery. So Agnes reluctantly agreed to do the pilot, and she demanded that the witch she play not be wicked, and that she would name the character herself. Hence, the name Endora comes from the bible as Agnes was a very religious person. In Samuel there is a reference to a medium known as "the witch of Endor". And there you have it Endora!.
By the way, I enjoyed watching that clip, I hadn't seen that movie in many years. It had a great cast of character actors in it. Agnes Moorehead, Richard Deacon, John McGiver (Many Happy Returns tv show) and Ray Walston. And Jil St. John, of course.