Jeez, monumentally scary!! Folks: as cool and manly as this looks let me strongly suggest that, should you find yourself in the situation of watching a helicopter do a medivac, that you find the biggest most solid looking tree or boulder and get behind it. That helicopter was operating at the absolute edge of its abilities. The military, especially, does that and is comfortable with it. That doesn't mean that you should be. A slight downdraft or power loss and all that torque would have been smashing against the rocks and there'd be shrapnel everywhere.
Like this:
http://www.youtube.com/watch?v=Lrccoe4agkAJust a thought... .
g.