I would beg to differ that that would be proof only on a high grip concrete surface like an old airport runway.
The surface also has little or no camber personality, so I believe that even for an average driver like myself (with the ABS fuse in my FED Elise pulled) that stunt would be possible in that scenario.
I believe Walsh is also a pro driver in a controlled theatre, meaning that he had foreknowledge of the situation(he created it), which is different than me getting caught out at speed on a track or contaminated public road surface.
On a US road course of asphalt/tarmac and camber built in at higher speeds a different approach would be necessary.
With a mid engine rear drive car there are two ways to lose the rear.
first is too much load on the rear tires at the peak of the slip angle, and second is not enough load on the rear tires(or superior front grip) at some point of the rear tires' slip angles.
Best drivers know which problem it is and exactly what and how much correction is required without losing too much time.
In a front driver you add a little corrective lock and use the throttle to pull out of the unbalance, which may or may not be a no-no in the Elise.