IMO, Young Witch, Witch and Mountebank would do an excellent job. Native Village would have an equal chance of hitting good cards and crap cards in those situations, so the cursing would gum up the works, just like you intended. Unless Native Village is the bane card, of course.
Sea Hag happens to put the curse on top of the deck, and I think that's a rather big deal. So long as your opponent has a Native Village in hand, which is a decent assumption for your second play of Sea Hag and practically a given by your third, you discard your Sea Hag, he discards his Native Village, and you take a VP chip.
I'm going to disagree, at my own risk, with Mic Qsenoch's opinion that the 10 VP matters. Sure, the game will probably end on three piles, but the guy with more NVs and Bridges has more control on when that ending occurs, and I think it's only a freak occurence that that person was AdamH this time. Six VP is nothing.. on a proper megaturn, Shecantsayno can simply play the very bridge he bought over SeaHag, use the +buy from that bridge to buy a Province, and VP advantage negated, except he got to use that Bridge for economy all game, while the Sea Hag was like, a zero coin Militia.