Your first impression is this will be disappointing, but this guy is thinking.
Two interesting comments:
I always think of wing-in-ground-effect as increased lift for flying machines. But, for downforce it makes sense it will augment (as he says).
Also, he talks about the big vortex that mfain mentioned on page 1 benefitting brake cooling. I never realized that before. Although the video never mentions brake cooling, votices have low pressure cores. He does insert his cfd plots showing the big vortex.
He talks about rotating the drag vector, but I’m a bit skeptical in this application.