There seem to be two threads going on here:
Some posters are talking about autorotations with an element of rearward flight BUT a forward flare and touchdown.
Others describe a full rearward auto with rearward touchdown!!!
I think most pilots would have tried the first but hat off to anyone who has tried and survived the latter!! The Bell 47 seems an ideal aircraft to do this with plenty of inertia in the blades. Would not want to try this in an R22 - not much margin for error.