I LOVE this commercial. I downloaded the HD version from YouTube and watch it frequently. I showed the guys at the dealer last night when I bought my Z and they all loved it too.
I think they picked the green for two reasons -- first, it's a Kawi trademark color, and second, it helps show the bike's lines better. I agree that black is the more sinister color, but you just can't see the lines very well. That's why I love my white/orange one.
Rob