Other than common courtesy to other passengers, is there a "policy" that requires the use of headphones while watching movies etc on an IPhone during a flight?? My wife was on a flight that had in the neighborhood of 90% empty (DL 1053, still airborne), with nobody within rows of her, and the flight attendant told her it was forbidden to "listen" as she was watching the football game tonight without headphones on.

More specifics when she gets home, but was just wondering if headphone usage is some type of rule.