Here's some good in-car video of one of my favorite race cars (Porsche RSR) on one of my favorite circuits in "typical Spa weather." The second driver gets out of, and back into, the throttle in mid-corner several times. Doesn't seem to affect his traction or line...
I love rain racing. For one thing, it's an equalizer. Back in the Cretaceous, at a rainy SCCA Regional, I watched a (2 liter) Porsche 906 hand a (5 liter) Ford GT 40 it's head, lap after lap--pulling away--until the course began to dry. For another, the cream rises to the top. Racers with the most sensitive butts, hands, feet, and inner ears, just drive away from mere mortals.
Jim Pace Motorsports has also posted a good in-car video of him lapping Road America in a Lola T 70 Can-Am car. It shows what squirrely beasts Can-Am cars were to drive. His second and third counter-steering trips through The Kink are fairly heart-stopping.