That's pretty standard knowledge. Overinflated tires incur a penalty in terms of longitudinal traction, but they're often better in terms of wet grip and cornering. If you want the best braking, underinflate your tires.
Also note: ABS. A rigid tire will "bounce" and trigger the ABS system more. If you adjust the suspension to make up for the bounce, you can shorten that braking distance.
Too bad they didn't specify what pressures were used in that test. Hmmm... sounds like something we can test on track next month.
Love the drifting truck sequence afterwards...