lol I don't know what to tell you if you think yanking someone out of the car, throwing them on the ground, cuffing them, roughing them up while they are cuffed, verbally berating, trying to force them down to a knee even after they tell you they had surgery on their knees, etc... is proper police protocol for not rolling down your window.
Even if you believe that police have the right to detain someone for not rolling down their window, I'm not really sure how you justify all that extra stuff when he wasn't resisting arrest at all.