Seattle fumbles the ball in the backfield on 3rd down, recovers for a loss and gets a fresh set of downs.

http://mfn1.myfootballnow.com/watch/1484#265739

That's interesting, looks like what technically happened is that it got recovered by Pittsburgh and then fumbled again, which is a change of possession. But, clearly the timing was such that Pittsburgh didn't have enough time to actually obtain possession - I'll make a note to look at how to make that work better.