Is that you at 34 seconds?
Notice how far your feet are in front of your body. I'd call that the most important thing you need to work on. Get your 1st most important thing right most of the time, then go to your #2 most important thing.
How to pull your feet back under your body?...that's the question. There will be lots of tips. I prefer to pull the inside foot back with a constant tension...pull, pull more, don't stop pulling. Drill by skiing with the tail of the inside ski off the snow and the tip on the snow.
Equipment can make the backseat problem worse. Boots where the cuff slants too far forward is a problem. The lower leg slants forward, the knee bends to balance with the hips back, and you're stuck there. If there's a way to make the boot cuff more upright, try that. Boots and bindings with the heel too high vs. the toe offer the same problem. If you have heel lifts in your boots, try removing them. If your heel is loose in the boot, use a tongue shim to hold the foot down. Some skis have the boot mark too far back for good balance. If your bindings have adjustable fore & aft positioning, try the bindings more forward.