The movie theatre business is so spooked by declines in box office in recent months that AMC, one of the biggest chains, is offering a money-back guarantee. If you don’t like “Cinderella Man” you get your money back. “The no-hassle money-back guarantee is a rarity in the business, where fans who sit through awful flicks usually leave with little more than bad memories. But AMC’s results are encouraging enough that CinemarkInc., another big exhibitor, is planning a similar promotion for the three-day weekend.”