Don't be so hard on yourself. We have all been there and gone thru the exact same thing at one point or another. The pony looks a good little horse she just knows she worries you enough that she can start refusing and running passed the fence.
You can go over it because we have seen you go over the x-rail. That fence is actually not much taller than the x-rail but I think you worry yourself over it.
You need to keep your eye up, lift your hands off the neck(grab a chunk of mane if you need to when you are actually taking off for the jump) and leg leg leg! Keep that leg on and be assertive with your body that YOU WANT to get over that jump. The second you second guess yourself all your aids go out the window and your pony knows it, that's why she casually runs right passed it.
YOU CAN DO THIS. You are an excellent rider, when looking at the video it's obvious that this height of jump is good for you as you have the foundations down pat. I think you're just going thru that inner battle of not being sure if you can, something we all go thru, every single one of us
Nothing can stop you from doing this