Man, I wish *I* had somebody to box with in-between classes. But most of us teacher types don't want anything to do with it, unfortunately, no matter how hard you try to show them the beauty of the game.
I'm mixed on the square-vs-T. I'm a kicker, so if I'm allowed to use my feet, I love it when my opponent's in the T (but nota bene, up-top, you suffer for it). But if you want to stay more square, you're going to need to really work on your counterpunching versus just crowding for a clinch, b/c a guy with a good stiff jab will be able to continuously pop you and slide right on out.
Kid already beat me to most of what needed to be said. Suffice it to say that I agree with all of it, ESPECIALLY the part about arm punching and pushing rather than hitting. That's the A-#1 mistake I see self-taught guys doing.
Specifically, concerning being light on your feet, AMF, you're on your heels, a LOT. Both of you are. I don't know about wrestlers, b/c it's been ages since I did that, but it's a big no-no in boxing, because it sinks your weight, and makes it nearly imposible to roll with a punch. Blue shorts can get away with that as a croucher. You're too big to do that.
When you punch, you let your guard go all over the place. The guy in the blue trunks gave you a REALLY easy couple of rounds there, rather than counterpunching. Now, the camera makes it look more obvious than it is in real life (the couple of times I've seen myself on film I wanted to throw up), but since you're arm punching and not rolling your shoulder, he had tons of opportunities to cross those jabs.
Also, Kid's #5 is actually a penalty called "dangerous boxing" and will get you thrown right out of the amateur ring. When you duck like that (and I'm guilty of it too, b/c I don't guard my breadbasket well enough and it gets frogged... but at 50% power, that's not an issue), you're exposing the back of your neck to an accidental elbow. People have died in the ring that way, and you need to make sure your guy with the camera is SERIOUSLY ragging your ass on it. Safety first.