This type of takedown is very good. In Brazilian Jiu Jitsu, it's often referred to as an "X guard sweep". Using this type of takedown shown in the video involves throwing yourself to the ground- not a great idea in most circumstances.
But the principle body mechanics you can see in this footage is good. You can use modified versions of this technique, from your back, to tangle up opponent's legs and keep your hips above theirs.
If your hips are above your opponent's, you are at the advantage. You can even see this in the scissor takedowns- they have to raise their hips up, entangle legs, and then let physics do the rest of the work. It does not take strength to use techniques like this (it helps, though)- it takes skill and timing. All about using body mechanics against itself.
You really need to practice the hell out of a flying takedown (or any flying technique)- they are high-risk, high-reward maneuvers, like spinning strikes.
In this case, I try to imagine doing this to someone on a sidewalk. You have to be very conscious of where you're going to land, and keep your chin tucked low to minimize risk of busting your head on the curb or a fire hydrant or any number of things. This is not something amateurs should practice with the hope of adding it to their self-defense tools. This is more advanced.
This would've been perfect for the White victim in this video: https://www.youtube.com/watch?v=IEiMjQ00jBQ
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