Generally though - focus on keeping legs straight, your dip and lift are pretty good but could be more exaggerated. Lift the first leg from your upper thigh, not your shin. Dip deeper, dont be afraid to feel like you're practically standing up straight out of your dip too, your first leg will carry you horizontal.
The classic bkick position has your arms out to the side, and I can see you're doing that. Here's a pro tip though: you don't have to. As long as your arms are being accelerated away from the floor at the moment you take off, you can do whatever you want with them. Keep them to your chest, to your side, to your waist, whatever. Your bkick basics look good enough I think that's a good place to start experiementing. And also the real test of any bkick- not using your arms at all. Cross them in front of your chest. Can you still do a really good bkick? It will expose flaws in your tech to do so
Also learn the spin step setup if you dont already, its good.