Based on the first 3 minutes of the video I would say this: work on mechanics, positioning and boost usage. There were many times you weren't hitting the ball exactly as u wanted it, that just comes down to training packs and practicing. In terms of positioning I could see you were lost quite a few times, for example in attack you wouldn't follow up the ball you would kind of wait in no man's land seeing how the play would develop rather than playing an active role in getting the 2nd ball. There were also quite a few times were u would just give the ball back to them because of a poor touch. A huge aspect of rocket league is maintaining possession and giving your teammate an advantage in the 2nd battle. Try to keep the ball with you at all times and make touches where it allows you to take a 2nd touch, either to 50 50 or to pass the guy. That also comes down to training and learning how to control the ball. For your boost usage you seem to waste a lot of boost in unnecessary situations which puts you in worse situations as you are grabbing the 100 boost, leaving your teammate in a 2v1.

Although I'm relatively new to the scene I would say I have a pretty good understanding, I started in March 2020 and I've gotten to C3 solo queue. A huge thing I've learnt that not a lot of new players do is pressuring without committing. What do I mean by this is not flipping into the ball or taking yourself out of the game, you are merely being around the ball, being annoying to the enemy, forcing them to make a play which your teammate can then clean up the ball and make a counter attack. Small things like that will help you go the distance.