Indeed. Ironic timing, I stumbled upon the Queensland Agriculture YT channel about the same time Fruitful Trees published the video. I believe that's TFF member Weiss' property in the video. I wonder what BSbullie would have to say (if he still contributed). I believe he was critical of this high-density plan.
That Queensland Ag YT channel has a bunch of good videos on various topics. There's another mango production technique they detail using trellises/scaffolding that looks ultra-productive, but not as visually appealing as the slim hedge.
I have five year-old seedlings in containers I'm about to plant on a North/South row with something in the range of 9-12' spacing. I'm putting them in the ground asap, hopefully they'll establish and I can graft to them late summer this year. I need to find 5 varieties with similar (preferably low/medium) vigor and growth habit, I don't want to have one lanky/leggy variety next to a stubby, short-internode one; I don't think that'll make for a very attractive hedge. Choosing the varieties is going to take awhile. Paralysis of over-analysis, that's how I like to roll....