Hillerbee is right: This is a maneuver for play/practice/demo only - no real application in the real world. Think: No matter which way the nose is pointed at touchdown, the *rotor* is still doing a downwind auto. Sure, you can flare harder because you don't have to worry about whacking the tailboom, but you still may touchdown with some forward speed...which is actually rearward speed relative to the airframe and skids. Damn, you better be good! I wouldn't try it, but I'd like to watch it done. From afar.
Pilots do like to play. Back in the '70s there was a demo pilot at Enstrom by the name of Mike Meager. At airshows he used to specialize in backward autos to the ground. Estimating the 50 knot attitude is not all that hard - it's about level, either way, right? Another Enstrom guy - a test pilot who later had a column in ROTOR&WING Magazine, whose name I forget (Doug Kott...something like that?) - also wrote about those backward autos to the ground. Says he did 'em too. Balls of steel, those guys.
Pilots do like to play (Part 2): In the 1970s I worked at a charter outfit in NYC that also had a couple of 47s doing spraying. Those spray guys would go out and play sometimes, challenging each other to autorotation contests. They'd do all kinds of crazy stuff: side flares to touchdown and the like, until they scared themselves so badly they'd quit. Hard drinking bunch. Balls of steel, those guys.
Pilots do like to play (Part 3): Then one evening the Assistant Chief Pilot of this outfit arrived in an Astar at the tiny E34th Street Heliport in Manhattan. He came in fast from over the river. Just before coming over the pad he flared. While in the flare, he pedal-turned around. Now he's moving backward, nose pointed at the ground, backing up toward the fence and elevated highway that bordered the property. He got it stopped and set it down perfectly - probably chuckling to himself that it worked out so well (and looked great too), and probably didn't think anyone was watching his little display of hot-doggery. But I was. (If I had tried something like that he probably would've gotten me fired.)
Pilots do like to play (Part 4): When I was young and stupid, I'd take an L-model in a 3 foot hover and get it going backward as fast as I dared (at an airport, obviously). Then I'd chop the throttle and land it. Good fun! I'm older now. Would I ever do such a stunt today? Heck no, just the thought of doing something that stupid scares me sillly. Plus, I'm not that good anymore. Trouble is, I only thought I was back then. Only dumb luck kept me from balling one up, for sure. That, and balls of steel.