The sequence in that video at 04:50 is just about the pinnacle of stunt flying and is an event that we will never see matched again. In theory, all he had to do while flying down the storm drain was keep it straight-and- level. Easy, except he had less than five feet of clearance on his rotor tips and even less clearance above and below. It is a pity CGI is taking over from real flying in movies these days.
Not sure if Mr. Kirsch is THE best, but he was certainly one of the most gifted (and bravest) pilots ever to strap on a helicopter.
500 Fan.