Because he makes extremely sudden and sharp movements which one doesn't normally do neither when driving nor when racing. If you do that in whatever car you have at 25 miles you can bet you will get a similar result. It feels like the driver was specifically testing for body roll.
Saidur Ali was driving one hand with a controller and holding a videocam in the other, and from cockpit cam, you can see he was cranking it pretty abruptly. I think the bodyroll is about right too,
I'm going to bring up the dreaded F-game, so no one take offense.
Even though Forza and I don't get along, Forza 4 showed off some amazingly lifelike car dynamics, which I haven't seen in any other racing game. Surprisingly, Forza always lacked bodyroll until F4, while Gran Turismo always had it until GT5, go figure.
Anyhow, the reason I bring this up is that in my struggle to come to terms with Forza 4 in my one-day retrial of my other racing games, the one thing that I still appreciate greatly is how well Turn 10 finally modeled the suspensions of street cars, and how precarious it feels to take them to the limit around turns. It really feels scary sometimes, as it should on a good sim.
In GT4, I recall how we would take a stock or lightly modded RX-7 around the Nordshleife as fast as we could, and that was a white knuckle experience. Reaching 140mph on the first long sweeping section, Kottenborn and Schwedenkreuz was always a hair raiser as the little RX tended to begin bucking from the numerous undulations, threatening to send us flying off into the guardrails, and often did.
I decided to try recreating this in GT5 last night, and was quickly frustrated. I don't know if the road was paved because it became too much of a headache for the Nurburgring operators to deal with idiots going too far with their cars or what, but everything I tried failed to give me a treacherous drive. The car pretty much stayed stuck to the road on all compounds, just making it harder to take turns as fast as I wanted. All cars that I tried, unmodified save for various tire types. They all behave kind of like Formula cars of various performance levels, built to be stable and fast.
Most race courses have fairly flat surfaces, and most games have tracks that are silky smooth. But in Forza 4 on Hockenheim with a stock Golf GTi, even with a manicured track, the car was a handful. Of course it helped that F4 has no ABS to speak of and for whatever reason, the perspective in Forza has always been weird to me, and I rarely can take a turn comfortably, while I can in every other racer but Enthusia. But regardless, the tame little Golf snarls and fights you like a tiger as you push it hard, and the tires jitter and complain loudly as you roast them in an attempt to force the car to take turns recklessly fast.
I love reading the descriptions of the guys who were lucky enough to experience this early build of the GT6 demo, and seriously look forward to getting the Academy version in July. I'm hoping though that my Forza experience is similar to the one I have when I get GT6 itself in my sweaty palms this holiday season.