Serious question:
What is it about the Mustangs that make them suddenly turn like that under hard acceleration? It seems like ALL of the Mustang crash videos have a handling scenario like that. Since this was on a track, I am assuming he didnt hit an oil-down or water spot.
I think it boils down to wheel speed and traction.
Back in the day, you had an engine that made peak torque at 2,500 rpm and had (at best) a set of BFG's that would give up traction very easily. So, we could spin the tires off idle and maintain control easily since neither the tires, nor the vehicle were moving at any kind of significant speed.
In modern cars - most especially in the Mustang - peak torque is north of 4,000 rpm and the tires will hold traction much longer than an old BFG will. So to keep the hides boiling, you've got to have the engine screaming, probably in second gear and moving at a fair clip. Lose your train of thought for an instant and let those tires hook back up when you least suspect it, and you get tossed.
Same goes the other way.... keep the wheel speed up high enough to not let the tires grab, and pretty soon you're doing 50-60 mph with zero control of the rear end. You can't really modulate the power being sent to the back wheels when that kind of power or wheel speed is involved. Or, let's say, your average numbskull driver might not have the skills required to do so.
Turn all of the nannies off on these cars and they can be pretty unforgiving. I thought I was a badass once with all my nannies off and tried to showboat. Yeah, she bit back pretty hard. Luckily, all I did was swing the car right around in an intersection where previously in any of my old iron; I could drift through the intersection like I was Mario Andretti. Not so much in the new Mustang. "
I think it comes down to that sense of calmness modern cars can lull you into. Like soccer moms in their SUV's that think they can drive through 8 feet of snow on summer tires and are completely baffled when they flip the thing ass over teakettle. Same as in a Mustang.... it doesn't seem that powerful until you try doing some flash maneuver. Then you learn that 450 horsepower is WAY different than the 160 your old Camaro used to put out.