You're a stronger 3.5 with good potential as a 4.0. Some things I noticed that I think make you a 3.5 is that you were hitting the ball right back to your opponent. Then when you came to the net, you hit a poor volley, and your opponent had all day to hit the passing shot. Once you hit the bad volley, you should have split step and then just chose a side (anticipating). Maybe you choose right, maybe you choose wrong. But, the secret is, give yourself a chance. Staying in the middle on a sitter is bad.
I definitely like your strokes. You have excellent potential to be a 4.0 and maybe even stronger. You need to move your feet. I mean really move your feet. YOU ARE LAZY...lol...I mean that in the most positive way. If you can split step and then learn to move to the ball, your game will improve dramatically. I honestly think in order for you to move to the next level, you need learn to volley better, you need to bring your opponent out wide on both sides of the court (and come in and finish the point), and learn to hit approach forehands, backhands, and slices. Other than that, I bid you good luck.