MEXICO CITY (Reuters) - The Mexican Air Force has released footage of what a UFO expert said were 11 invisible unidentified flying objects picked up by an infrared camera as they whizzed around a surveillance plane. A long-time believer in flying saucers, journalist Jaime Maussan told a news conference on Tuesday the objects were real and seemed "intelligent" after they at one point changed direction and surrounded the plane chasing them. "They were invisible to the eye but they were there, there is no doubt about it. They had mass, they had energy and they were moving about," he said,...