I've seen lots of photos of airborne refueling, but always from the side of the boom operator. I've never seen the fuel nozzle like this. It looks so weird and cool! I like how the nozzle comes out of the flying boom, like the mini-mouth coming out of the alien's mouth.
The flying boom is attached to the rear of the tanker aircraft. The attachment is gimballed, allowing the boom to move with the receiver aircraft. The boom contains a rigid pipe to transfer fuel. The fuel pipe ends in a nozzle with a flexible ball joint. The nozzle mates to the "receptacle" in the receiver aircraft during fuel transfer. A poppet valve in the end of the nozzle prevents fuel from exiting the tube until the nozzle properly mates with the receiver's refuelling receptacle. Once properly mated, toggles in the receptacle engage the nozzle, holding it locked during fuel transfer.
The "flying" boom is so named because flight control surfaces, small movable airfoils, are used to move the boom by creating aerodynamic forces. They are actuated hydraulically and controlled by the system operator using a control stick. The operator also telescopes the boom to make the connection with the receiver's receptacle.