I'll be the contrarian here. There
IS such a thing as over-pruning, and in my humble opinion, the video demonstrates that. As someone who has killed
fruit trees by over-pruning, I find myself sitting up a bit and cringing as I watched your very aggressive technique.
The biggest concern with being so aggressive in pruning is sun-scald to the lower branches and base of the tree. Perhaps the sun isn't so strong where you are growing his orchard, but I know that I've killed mature fruit trees by taking out more than a third of the over-story branches in one growing season and exposing the underlying scaffolding to harsh UV rays that burnt the bark and created an opening for pathogens to enter the tree. The only exception to this (in my
experience) was topping avocados when they get leggy and lean-y as they grow over 20 feet tall. But even then, after topping an avocado, I'm careful to paint the exposed trunk and limbs with a diluted latex paint solution to protect from sun-scald while the
canopy regrows.
Perhaps those small trees will quickly fill-up the newly opened space and provide enough leaf-cover to safely shade the branches below. That's often the case, in if so, you won't see the UV sun damage to the bare, exposed bark. But if not, those bare branches can quickly get over 120 or even 140 degrees on a hot July or August day where the sun directly hits them for several hours. At that point, you're practically boiling the tree cells alive. The vascular cambium and secondary phloem are sensitive to high temperatures and if they get over 110 degrees, the cell membranes rupture and die.
So, yes, prune aggressively. But just as you wouldn't send a child out to play all day without adequate sunscreen, a shirt to cover their shoulders, and a hat to keep their little ears and nose from getting burnt, so also young tree limbs need some protection from the harsh rays of the sun.
Please do a follow-up video to share how your young orchard is doing in the years to come.