That requires some pilot-shooter coordination right there but it is easier compared to engaging from a navy vessel at high seas. One second the target is there, next second is not. Onemight have to take the shot w/o actually seeing the target. The only good thing at sea is that the wind is steady but the rest are all sort of moving variables as neither your target nor your position are stationary. Let me see if I can find a video of the training targets.
Also found this.... 2 Navy Snipers VS 38 Somali Pirates - YouTube
As we watch Sergeant Kim (most common family name in Korea) of the South Korean Special Forces shoot his Steyr SSG PII from the door of a UH-60P (S-70-18) helicopter what can we learn?
The helicopter is fitted with the External Stores Support System (ESSS) with an Extended Range Fuel System (ERFS) attached. This is pretty typical of such aircraft dedicated to special operations.
Making those shots is difficult under any circumstances but if you have to pick a helicopter to shoot from the UH-60 Blackhawk is a good choice. The UH-60 is equipped with an Automatic Flight Control System (AFCS) that incorporates a Stability Augmentation System (SAS). The SAS allows the aircraft to maintain a near motionless hover creating a relatively stable shooting platform. However the vibration of the rotor system remains.
I was unable to identify the telescopic sight SGT Kim was using.
I have to admit that shooting from a hovering Blackhawk isn't very stealthy and can be downright dangerous especially if your adversary is inclined to shoot back.