Looks like it must have been a historic series. I wouldn't be surprised if he was running old school bias ply tires explaining the extreme slip angles. He looks to be a pretty competent driver, and i beleive the tires likely explain the driving style. Not sure he would be driving the same way on modern radial slicks.

 

He's got casters for rear tires!

 

You are spot on on this. This video and another one from the same event was discussed in the racing forum a few months ago. It is historic racing, he was on a qualifying lap, SWB 911 on bias ply tires. Pretty much a recipe for supreme oversteer

There is an interview and an article I read somewhere where the driver explains just that and the need to drive it this way for a fast lap.
This guy is super skilled and if one is looking for an example of what throttle steer is, I think he demonstrates very impressively.
Wish I have the cojones to be able to drive like that

EDIT: there is more on this: http://jalopnik.com/5894294/ride-alo...circuit-de-spa

 

bias ply, ok ok... giant *****!

 

Seen him driving a few times in real live at Spa Franchorchamps (love that track, who doesn't). I think I might even recall this specific race (yes race if my memory is correct). To see that guy go thrue Eau Rouge is off the chart. Speed differences and quality of drivers is massive sometimes in these hsitoric races.