I suspect that what's more likely to happen is that the board will wedge in a hole, stop moving, and you'll simply find yourself stepping forwards off it.

The standing posture means that you're braced for a step anyway, and the speed is totally compatible with your mark I human undercarriage system. It's not like you're on a skateboard going at 30kph. Plus you're not fastened into it.

I actually think it's a really interesting and subtle piece of design. I want one. (Plus I have to admire anything that looks quite that stupid.)

Agreed. As a 20 year+ street skateboarder, I can tell you that even with larger and softer urethane (85-90A) wheels, a pebble the size of a tic tac will send you to ground rapidly. The key is to over time develop skills of controlling weight on your board. I suppose this design could be modified some, but more likely that the driver/rider will need to learn some skills from skateboarders :)

I have a piece of titanium in my orbital bone from when I ran over a little rock when inline skating. If this thing hits a rock you'll go flying. Really hard.

Where really hard is 10kmph.

I'm not sure why this isn't one of the top comments. The wheel size is a nonstarter.

In the video he does run on tiled stones even and over a small gap, see 0:39 to 0:49. It looks like he's not struggling but it's such a closeup that you cannot see if he lost balance or not afterwards. I'm still very skeptical though, that gap would be quite hard to cross on a skateboard without a small jump and on a skateboard your center of gravity is almost 2 feet further back than on this thing. Maybe the propulsion in the wheels help.