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It's a combination of a 3d layer for the main rotor, a 3D layer for the tail rotor, and a still with the helicopter body masked out as another 3D layer, and a background layer. You create the blades, rotate them so they match the perspective of the original photo, spin them with motion blur, then add a camera and put in a little camera movement. It's not that hard if you think in layers and 3D.
Taking one more look it looks like there were also 3D layers created and spun for the rotor mast for the first helicopter. Do a Google search for "The Kid stays in the picture tutorial" It's the same idea with replaced moving parts. Take a look at this. Do a little research on 2.5D animation.
Rick has given you good advice, but here's a thought: You could ask in the comments of the video that you are asking about, so the creator has a chance to tell you himself how he did it.
Thanks, I did do that before I posted here