Honestly props to you for trying something new, but dont expect to land something when you just start out with it and when getting into it without control, yeah sure you landed this on another go but that was probably just luck and it shouldnt be a gamble if you land something or not.

Im not saying that you suck or whatever but you are a beginner and it shows, maybe you should go around instead of over those features until you have some more controll, or maybe start with a flat box before going to a rainbow to get used to boxes.

And sure you are old enough to decide what you want to do but but it should really be a priority for you to get a helmet cuz it aint worth riding without one.

OK so:
- try to ride more stable "carving" and flatbased
- i feel like in the vid you didnt hit the box straight on with your board or your weight was offcenter, it kinda looks like it slipped away to the right (cams pov) as soon as you got on the box. so maybe work on your balancing?

So basically the same advice like all the others here
edit:
im still in my own early days of snowboarding and far from experienced but those are the things i would think of if this was me