Based on your video, it looks like the balance is probably more of an issue than your flexibility.
To practice the position, stand on the ice facing the boards, grab the boards and pull yourself back away from the boards while pushing your skating foot forward, squeezing your shoulder blades together, lifting your chin, pressing your belly button down toward the ice, and raising your free leg behind you and turning it out. That will put your skating foot in front of your hips at this angle \ instead of directly under your hips at this angle |. The effect is that it pushes your hips down, gets your weight away from your toepick and allows you to lift your free leg above hip level without pitching forward and tripping. Even when you are out on the open ice with nothing to hold onto, it should feel exactly the same, like you are holding onto something and pulling back from it.