You've got all the makings of a solid second serve.
What you lack is upper body turning more sideways at prep position....you still face your opponent. Your feet alignement is good, but your upper body is facing forwards. Instead, line up the shoulders so they face the same as your feet alignment, to get more rotation into your swing.
You swing is really slow, and disjointed. Is your racket too heavy for you? There is a huge non control element between your racket and your forearm. You seem to grip nice and loose, but you are disjointed at the wrist, like it's a rubber band connection, not a solid controlled, but loose connection.
You hold waaay down at the buttcap. That is good for increase leverage, higher strikepoint, and more racket head speed. BUT, you have no swing speed, and it's possibly due to where you hold the racket. Could it possiby be, your racket is too heavy for your strength, so you can't swing or control it?
I always "claim" I have a really fast serve, for my age and build. I can serve just as hard by choking up the handle 2", because it gives me a lighter racket, shorter fulcrum, so I can swing my arm faster! I do choose to hold down at the buttcap for increased strikepoint height and more RHS with less arm effort.
BUT, your swing is waay to slow right now. Maybe post a vid of you swinging normal speed.