+1 to the above statement - better camera location.
Next time when you're recording try multiple different locations and do like 5-10 serves each time. So from directly behind, on your left side, on your right side and maybe on the other side of the court facing your front. Then we can see if you're fall away from your ball toss, hip rotation, feet position, shoulder rotation etc..
From what I can tell, you're not getting enough drive up into the ball. It almost looks like you've got chains around your feet if you sorta understand what I mean.