The 3L turboed lump in the Z4 has masses of torque, so I wouldn't be too quick to dismiss it if I were you. Given that Nismo of late (with regard to the road cars at least) have become a sanitised version of what they used to be, a few extra ponies and some above average suspension bits really won't make that much difference in the grand scheme of things, although they will make for a better connection between driver and car.
Having just seen that video again, check out the arms of the driver in the Cayman: They're all over the place towards the end of the video. I'm not saying that he can't drive for peanuts as he may well simply have gotten bored by that point, but that's not what I'd expect of a top (or even average) driver. The more I look at that video, the more I'm convinced that it was staged for shock value so that people would watch it.