Ground effect demonstration - GIF

[Toolmaker51]

I also think that demonstration is more about the updraft created by the artificial cliff and the apparent wind created by walking. It is like slope soaring. Wind blowing onshore, hits a cliff along the beach and deflects upward. Bird, hang gliders, pilots, all use it.

Pelican the pelicans are using ground effect. They are also so cool to watch.

Sept 1997. Return trip from Catalina Island back to Long Beach CA, an albatross flew parallel to my course and matched speed, displaying very little effort to do so. Even turned it's head a couple times with a "that's all you got?" look. I think this went on 5 minutes or more, until throttled back entering bay traffic.

Up till then, I was trimming twin outboard V6 Mercury 2 stroke 225hp into most perfect plane attainable over a wind astern 3' chop at 5500 rpm redline. That 31' 6" Chris-Craft Scorpion stand up center console did 60mph in those conditions, broken water ideal for that modified V hull.
So asked why 3 of us partnered on that boat. 2 of us liked offshore fishing, and each a hotrodder.
I told people "because Ferrari's don't float..."