Driver of that S3 should be reported for Dangerous Driving. Yes, technically the old fella in the Merc is at fault but quite clearly the young rude boy is speeding (quite excessively) and it's clear he has neither any hazard perception skills nor the experience to get himself out of that situation. The fact he's tried to steer around a car leaving a junction shows all three of the above points. He's a class 'A' dickhead.
I NEVER speed round town but if I'm out in the sticks and pressing on a bit, as soon as I see a car at or approaching a junction or hazard, I ease off - even if only slightly - assess, and prepare to stop. He needs a ban and some humiliation.