Brett Velicovich was one of an elite handful at the center of America's covert drone war. During one four-month period, they removed 14 of the 20 most wanted terrorists from the battlefield in Iraq. Velicovich joins "CBS This Morning" to discuss his new book, "Drone Warrior: An Elite Soldier's Inside Account of the Hunt for America's Most Dangerous Enemies," and what it was like to hunt ISIS leader Abu Bakr al-Baghdadi.