The concept of VRS is intriguing, all the more so because of the miseries of the V-22 these days. The web site I put up attempts to explain the basics, I will try to add to it as we see new questions (such as this!)
Autorotation is called the windmill brake state, since the flow (going upward through the disk) is driving the rotor, and the rotor serves as a windmill. There is no such thing as VRS while in this state. When the pitch is pulled at the bottom of the auto, the rotor goes from Windmill Brake State to normal powered state, but the descent rate of the helo in this brief transient region is nowhere near that needed for VRS, nor do I know of VRS in auto touchdowns as a problem when we do the procedures during development test work.