I find the best part of all to be that there are no batteries. That's a lot of extra weight gone, a lot of extra complexity (battery cooling etc.) gone, a lot of extra cost gone, and a considerable ecological impact gone. I'm very very impressed, and I hope the vehicles are successful.
I watched the video and I'm a bit confused by the hydraulic component. I assume that the pumps are there to convert velocity to pressure and vice versa, but how do they work? Is it as simple as a vaned fan, ala turbocharger, spinning the pump (or vice versa)?
Edit: the more I think about this the more it tends to stand a lot of my hypermiling techniques on their head. If I want to use air power a lot, I will have to stop a lot! No more timing traffic lights.