i had a strange incident that is kinda the same to this too. Its not as bad as this but the other car was absolutely stupid.
Im out for a random drive one rainy evening, done some nice random lanes, when i come up to a town. Through the town im keeping to 30, then someone pulls out and only does 25. Fair enough its annoying but its wet and i guess 30 is not a target. I drop back and carry on at 25. A few minute later a focus Mk2 joins the queue, only this guy follows me so close i cant even see his headlights. As we come out of the town, a NSL sign is in the distance, 300-400 yards away i guess. Obviously im now preparing to overtake the 25mph driver but will wait till the NSL comes. around 200-300 yards from the sign, the focus screams (well as a 1.6 screams i guess) past both of us, almost doing a head on with a car coming the other way.
I was shocked with his actions for a moment, but carried on with my planned overtake as the NSL sign came. Upto 65-70mph (yes i know 10mph over... shoot me), and around a few bends the Focus trying its hardest to pull away as if it was some sort of race, then with a long straight he boots it up to, i estimate 80-90mph, before coming to a slight kink in the road. Being Mr Lewis Hamilton, he dabbed the brakes mid corner

, over steered, fishtailed and more over steering down the road for what seemed like ages (about 6-10 swings i guess). At one point he was at least pointing 45degrees off the road. I took the corner at 70 (with absolutely no loss of grip), straightened up then applied brakes to watch this "show".
Obviously the guy thought i was racing him, but i was just as much frustrated and wanted to make progress as he did, i didn't overtake the slow car to chase him down to whine about his overtake on me, I just wanted to get on with my drive just as much as he did. The problem is, if he had crashed i would have probably been at some sort of fault for "racing?"