That’s an Eurocopter EC135, which is being used by Bond Air Services to do windmill farm maintenance in the United Kingdom. I’m sure they stop the windmill before going up–unless the stop mechanism is the thing that is broken–but looking a the scale of that little man going down, it’s quite scary anyway.
And here I was, thinking they had elevators or really long stairs inside.
Update: As you can see in the crazy video, the reason is that these wind turbines are in the middle of the sea. [Flight Global–video thanks to Gitemsteve]