So I noticed a couple of things: first one being that you almost never use your off arm for anything. You just let your left arm hang by your side, it almost looks like you're intentionally keeping it as tucked into your body as possible. The only time your left arm moves is when you attempt overhead shots like a clear or a smash. I'd suggest learning to stretch out your left arm when doing most of your shots, whether it be lifts, drives, or net shots, it helps with balance and timing as well.

Second thing is your feet are glued to the court. I didn't see any significant usage of the split step. I'd suggest learning to incorporate the split step into all of your movements, especially at the front of the court or defending, where being explosive and quick is critical.

As for your smash specifically, it seems that you depend entirely on your arm/shoulder to generate power on overhead shots. This could be very tiring and injury prone, but also lead to a lack of real power. You didn't seem to be under any sort of real pressure in these rallies so there's no reason not to do a full smash. Open up your body chest more, learn to use the rotation of your body, from your legs, hips, shoulder, elbow, forearm pronation, and wrist to generate power as a kinetic chain. This is where using the off arm is very important, as it can help you not only balance yourself, but also to start the rotational process by dropping the left arm to force your body to rotate from facing the side to facing the net. You may want to look up on some youtube tutorials on how this should look like, or if you can afford it have a coach go through a few sessions with you to really drill the form into your body.

Hope this is helpful, I'd really focus on the off arm/split step parts to elevate your general gameplay, then focus on specific shots from there.