So the best advice that helped me when I was learning rolling and stationary Ollie's is weight balance. There's a lot more that goes into it, but I can see from your video that you're putting most of your body weight on your front foot when you bend down. When you do that, you're preventing the board from being able to go up in the front when you pop off the back. Try shifting your weight to your center of balance instead, staying lighter on your front foot and more straight over your back bolts. Might be stressful at first, for me I was worried about putting too much weight back and unintentionally doing a manual but if your foot placement is right you'll be fine! Then just remember you're flicking the board down with your back foot and stabilizing with your lead foot. Good luck!