A YouTube video posted Sunday purports to show the stealthy RQ-170 Sentinel drone made by Lockheed Martin Corp. flying at dusk in Nevada. The unmanned aerial vehicle, nicknamed “The Beast of Kandahar” after it was spotted in Afghanistan — presumably to spy on such neighboring countries as Pakistan and Iran, is flown by the Air Force on operated in conjunction with the Central Intelligence Agency. Iran in 2011 reportedly captured one of the vehicles, much of which remains classified.