Madeline Murphy remembers the instructions she was given on the set of “Jumanji” when she was an extra some 30 years ago: “Pretend you’re frightened and you’re screaming because an elephant’s coming after you. ”So, that's what she did in the Central Square of Keene, New Hampshire, running back and forth, over and over, on a long day in November 1994. “I was pretty tired by the end of the day, and it was cold," said Murphy, 61. She got a check for $60. 47 — and several seconds...