Yeah I've seen that one, thanks.
What I'm after is two people, arse-to-arse doggy style, with one person's cock going back between legs into the other person's anus/pussy. Presumably this person would have to be pretty well hung to have enough cock to both a) reach back past their own arse cheeks, and b) reach into the other person's orifice. Mine would possibly be long enough, but in no way can I even point mine down when erect, let alone back behind legs like the person in video earlier.
I've seen at least half a dozen hung people get blown from behind this way, so I reckon it's possible.