Another video with more tufts (I need a lot more pearl cotton yarn than I thought), and with the blower slightly higher up. (I'll get a second blower later this week.)
I still don't think this is an accurate representation of what would happen when the car is moving through the air, like in a wind tunnel. But, it does show the reversal at the wiper pocket, and the stagnant point is fairly obvious. There is a lot more "lateral" flow than I would have guessed.