Looks like it works pretty well despite the low set floor, and I think that it could be quite useful for many people -- anyone that has to delivery or transport to places that are on a dirt or unpaved road. Remember that its not for off-roading, but it can go off-road, if that makes sense.
Not sure how they actually did it though. Would be interested to find out though.
It's an aftermarket conversion, not sure how long until there would be either a local conversion for the ProMaster (in a similar arrangement to those ones made by Quigley in Ford and Chevy vans) or a factory fit.