You've got a case of happy feet. I count at least 2-3 steps in each serve.
The first is the large one from platform to pinpoint. Since you have such a large pause at that point any momentum from that movement is lost.
Then you have an additional 1-2 tiny mini-step/hops with your leading foot. The intensity and height varies from remaining in contact with the ground and barely lifting to actually lifting off the ground...the first occurs most frequently and the second on occasion. The first occurs during take back and the second during up swing. Again, their timing and duration adds nothing to your momentum and result in an unstable hitting platform.
How did I notice this? Well, in the last 12 months I've had THREE different teaching pros say the same thing to me. And they were right!!!!
After the third guy told me this in the fall I decided to take this seriously.
I now serve consistently with more power and FAR more accuracy than I did previously. My left knee and right ankle are too damaged to perform a full leg push up and into the ball. I've done it, it works great, but after several sessions it hurts my knee.
I think we have these little happy feet hitches to give us some slack on core turn. I have a friend with a similar problem but even more extreme. She has this huge wind up and then...STOPS! Full stop. Frozen. And the proceeds to whack the ball really hard and inaccurately.
These happy feet can cause problems later in the stroke, so before worrying about anything else get your footwork stable and smooth. I can suggest that with confidence because my feet weren't just happy, they were ecstatic!
Watch the videos closely and you'll see these tiny little steps and stops and how they effect your swing by creating hitches in your balance.