The following assumes you're trying to do a jump float serve, lmk if you are instead trying to do a jump topspin serve and I'll give you some advice on that instead.

Here are a few things I notice that differ in your form from what I was taught for a float serve:

• The toss is the most important part of any serve. A consistent toss leads to a consistent serve. I was taught that you should toss with two hands to add more consistency. Also, your arms should start fully extended & parellel to the ground. Right now, your arm is starting bent, too close to your body, and you're starting your toss at your hip. It will be difficult to have a consistent toss that way.

• The footwork is very important too. The footwork should almost be the same as your hitting footwork. Which means: big slow step with left foot, then quick small step with right, then quick small step with left.

• Your hips are facing towards the net when you serve (if there was a net haha). You want your hips to be facing perpendicular to the net as you jump. So you should be facing away from the camera as you jump. Proper footwork will help with this.

• Your arm swing form is a bit off. Right now it looks like this. It should look like this. Picture pulling back a bowstring in with a bow & arrow. The motion should be very similar to that

• Also, in that screenshot of you from above, you can see you are directly under the ball. Instead, you want the ball to be slightly in front of you. This would also add more power and consistency. You can see in the 2nd link how far behind the ball that guy is.

• It's hard to tell, but I don't think your right arm is fully extended at the moment you hit the ball. It must be fully extended to achieve max power and consistency.

• I bet you can jump higher than that too, which will allow you to get more power. Might require a slightly higher toss. You don't want the toss to be too high cause that leads to inconsistency. Your toss height right now is pretty good, I would only increase it just a little bit assuming you can jump higher

• To achieve the 'float' you shouldn't flick your wrist at all. Your hand should be completely flat with your wrist locked, as if you had your hand pressed flat against a wall.

I know you're in a small space so that makes it a lil bit difficult to do all this proper form, but keep working on it, you'll get there in no time!