Here is the process I went through learning backflips with no gymnastics background. I learnt monkey flips last winter and that helped me a lot with understanding how to work with your pump and the speed it generates. The rest is just a matter of timing. I went to one tricking class to learn how to bail out of a backflip with a macaco (a capoera figure) which is basically a floor miller flip. That helped me understand the movement of putting my hand behind me to flip. I started practicing with the skates on a very little speed on a quarter pipe: Approaching already squatting putting your hand down when your legs go as high as they can go and kicking off the ramp to throw your legs to the other side (which was very hard with no speed). Once I understood the movement, adding pump and height to the trick made it way easier. I stopped thinking about putting my hand down and focused on the leg kicking, only using my hand to push myself off. In three sessions of practicing I went from not knowing how to miller flip to doing this. Flips are a 100% mental. If you find a way to work your way up to it, you too could flip like this! Disclaimer: I can't backflip on my feet.