Lived out in the sticks for a while and our giant ass 1km farmland was am enforced safe zone from hunting, don't need dudes shooting guns in our yard or laying traps that could kill our animals and also everyone there was vegan. Anyway, this made our spot where deer could tske a breather and relax a bit and over time they got a bit more comfortable with us. I can say for sure, deer with their guard down are really really silly. They have fun
I found a YouTube link in your post. Here are links to the same video on alternative frontends that protect your privacy:
People in the video comments are speculating that the deer has chronic wasting disease, which is depressing as fuck if true.