With "No Drone Zone" signs superimposed on the field and in lights outside the stadium, the message couldn't be clearer. And it's not entirely unwarranted. People are using drones to film more and more sporting events, and while the NFL has an overhead camera system already in place, drones offer cheap aerial coverage for less-well-financed college and high school programs. Not to mention your average superfan. Last year, British police arrested a man for flying a drone over a Manchester City versus Tottenham Hotspurs soccer match. There's a safety concern with drones flying over crowds, but sporting events also have strict rules regarding filming and copyright, so that's probably at play here too.