I'd be a little heated if a car got that close to me. All of them are idiots, especially the guy that's riding two up. Cool vid, none the less.
And for the record, it only looked like the GT3 was keeping up when they weren't on it, or slowing for traffic. The GT3 should carry much higher corner speed though due to the credit card sized traction of a bike. Towards the end of the video they break free and check out on the GT3.