I'm surprised everyone is so impressed by the old leg in backpack take down technique . At least in our BJJ academy it's one of the first take down we learned and when the class is full of newcomers and the theme of the week is takedowns they teach that move .
It's pretty simple and safe and isn't as impactful as hip throws and wrestling takedowns . You seat belt then weave one leg between opponents legs and let gravity do the rest . The hardest part by far is actually getting behind the opponent like that , and that's why I've never even tried it in a real match.
It's nice too because the way your legs are positioned all you have to do once you hit the ground is stretch and lock your legs and your opponent either opens up and straightens too (allowing you to get second hook in) or get his groin muscle ripped
The hand fighting though was amazing , and that's where world class and hobbyist differences are apparent