Why isn't debris a factor in this demonstration? A tree hitting your house a 15mph will do damage. As the tornado destroys more homes, it picks up more debris and increases its potential for destruction. Was this demonstration created for an elementary school class. Step it up CNN.
There are small changes that can be made in building codes that can improve numbers. I thin 220 is probably fine for homes. It would be good to possibly relook at schools. I know, for instance roof strapping is required for homes in certain building zone. Maybe there are fairly minor framing changes that make more sense than marble floors.