First thing I do to correct a hop is widen the rear. But I’m not sure how wide you are already. A good baseline rear track width is 1390mm or 54.75″.
But it must be said, a kart will never really work or flex properly if you aren’t driving it at the limit and from this video, you aren’t even close. The best advice I could give to a newbie would be to set the kart up neutral and just pound laps before adjusting the setup. It’s good that you are picking up on these things you’re noticing in the handling already, but a lot of handling woes will go away themselves once your driving is on-point.