I'd never seen this before, and I'd always wondered what happened to him. If I remember correctly, going from the commentators on UK TV, he started the final lap 15 seconds ahead of Hamilton and had roughly matched his laptime on the previous lap. But, very famously, was overtaken on the final corner. Well the answer, amazingly, is nothing much. It just got too wet. He didn't spin, he didn't go off track, he just ran out of grip. Sorry if people have seen this before, I never had.