Here's my take...
(1) I see a lot of inconsistency in location of front foot plant as well as the angle of the front foot when it plants. This is an indication of inconsistency in other aspects of his mechanics. It should improve as his mechanics and timing improve and become more consistent. So I would focus on other things.
(2) I also see inconsistency in the back foot - some times it drags and some times it lifts off the ground. Most of the top pitchers in the game drag their back foot until ball release. Doing so is an indication of the head and shoulders staying stacked upright into release (as opposed to getting out front too soon/too far) and the result is shoulder rotation around an upright spine.
(3) I see too much side-to-side head movement. He starts off standing tall and then adjusts into a more athletic posture by leaning forward (toward 3B) at the start of his stride. But as he strides he leans back (toward 1B). This movement represents wasted energy and it contributes to incosistent foot plant as well as inconsistent release point.
(4) I see a lack of momentum which, when coupled with the head movement toward 1B, results in the early foot plant and short stride others have noted.
(5) I see the glove arm dropping too soon leading to early shoulder rotation. Ideally, the glove is still up in front of the torso at front foot plant. Building more momentum will make that easier to do by adjusting the timing of the event.
My recommendations would be as follows:
(1) Start in a more athletic posture to reduce head movement and improve consistency. Bend the knees slightly and bend forward at the waist. Try to keep the head moving only toward the target.
(2) Get the hips moving toward the target (sideways) sooner and faster. Start with small adjustments. I think the kick toward 3B in the knee lift makes the knee lift slower so I would eliminate the kick. Make sure not to sacrifice the height of the knee lift.
(3) See what having a faster tempo does to the glove arm. If it is still up in front at foot plant, you're good.