these are demo units. so i guess these are specially designed Wiis who either have:
1. another DVD-Setup to play special Demo Discs only (which is the easiest way for nintendo to send new demos and still have no leaks on the internet
2. channels for the demos (would be better for customers to choose between the games, but very hard for nintendo to setup as they need to connect every demo unit to the net and let them download the newest demos etc.. but it would be super-secure).
3. they send normal Wiis with disc which contain demos (not like the SMG in the usa which was the whole game)
i think they will pick number one.