No, you misunderstand what I said. I'll post another video....
Yes, the glass is coated to create the "refractive index" you described. The laser never touches the water droplet on the windshield because the laser never leaves the interior of the glass windshield. The laser heats up the tiny area where the water droplet sits on the windshield to vaporize it using the laser's energy. The laser energy is at the frequency of resonance of water so the water is efficiently vaporized. The laser is not in the visible spectrum so you cannot see it and it will never leave the interior of the glass. The glass is not really glass but ALON (transparent aluminum ceramic oxide nitride) so it has very low specific heat. Therefore, once the car is stopped, the laser turns off. If you touch it after the car stops, the glass will be cool to the touch due to it's low specific heat.
This is hard to understand using text. I will upload another video.