I'm an EE, and I have serious doubt about this actually working nearly as good as they are putting it. This sort of stuff is hard, even with purpose built radar systems. I'm working with angle estimation in Multipath environments, and that shit fucks your signals up. This may work it you have extremely precisely characterised the target room and walls, and a ton of stuff around it, and then don't change anything but the motion of the people. But that's not practical.