Spatial disorientation, I know the feeling flying IFR. Without instruments flying is impossible. I figured that hillside came out of nowhere for that pilot.
Particularly when that is a lot easier in a helicopter than an airplane. The helicopter he was flying seems like it would have been equipped with a full set of instruments suitable for IFR flight.
In my opinion every VFR pilot should have at least some training in how to survive an unexpected encounter with IFR conditions.