Ideally you want it up from the ground so it's at the height that you are when on the face of the jump/getting into the air, which would be roughly the same as if I were holding it at shoulder height I'd estimate.
Hmm, so you'll need a proper tripod then, with an ipod clamp of some sort. I've always bought Manfrotto tripods because that's what everyone else did at the time :) ipod mounts though, no idea. A quick google shows the "best ipod tripods of 2020" but I'm guess you want actual user experience.
Ideally you want it up from the ground so it's at the height that you are when on the face of the jump/getting into the air, which would be roughly the same as if I were holding it at shoulder height I'd estimate.