You didnt fully utilize full body transfer movement (or what it called... Im completly blank
Kinetic chain.
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Badminton insight, tobias wadenka and other channels all have videos on correct smash technique. Start with, the split step (small mini squat) with a stance facing the net, do a few chassé steps in the direction of the shuttle until you get under and a bit behind the shuttle.
As you are moving, get the non racquet arm up like you are doing and get the racquet arm ready (elbow to the side, correct grip, somewhere around right angles between elbow joint and also an angle with the wrist and be RELAXED).
Plant your non racquet foot in the ground and push with your right hip. At this point, this is where the kinetic chain theory happens. You transfer energy through your feet, lets, "trunk" (torso) and then into your shoulder and wrist in one motion. It's the same motion as throwing a spear or tennis ball.
My final tip is to squeeze your thumb and first finger just before you make contact with the shuttle. It gives even more power to the shot.
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From the clip you showed, the shuttle got a decent downwards trajectory and your racquet ended up in the right place, and you used your non racquet arm for balance or pointing at the shuttle well.
Try doing what I described in the first part of this message. Exactly as I described. This means you don't want your left foot leaving the ground fully. You're essentially losing loads of power by attempting a jump smash with the worlds tiniest jump. Sorry if I am being harsh, but that it what it looks like. You're losing a lot of power by doing that. Also, you seem to start your swing then move your right leg / hip. That's also a mistake.
Give it a try and let us know how it goes. I would be happy to give you face to face advice and practice. I am about 45mins - 1 hr train or drive from London and can PM you specifics if you are interested.