ok for first attempt this really is not bad at all. in the first one i assume you used like youtube flash kick tutorial so i wont comment on that. the cork itself isnt bad but the tech is kinda off and so you end up with your knee in your armpit which doesnt look great. its hard to explain everything in text so im just gonna attach a rpl of me quickly doing it with better form that might help. for the flips rpl there are a couple big issues stopping you from doing the backflips well.
1. you're extending ankles too much. they should only really be extended enough to make you lean back, then again maybe 10ish frames before you hit air. 2. the hips are way too contracted. 3. your arms are raised fully way too early.
ideally in any trick you want your joints to be maximally extended or raised right before you hit air. since you have the opposite in that your ankles are fully extended and arms fully raised way before you hit air, you gain very little momentum. if you continue its very important to try make everything sync up in that sense.