#6 - he is just asking for advice. Only because we have more hours then he probably does - that doesn't mean he is not welcome here.
This is not a scrim I suppose, i'm guessing tf2 lobby. While I understand you wanted to pick a match where you look in a good light, completly lobby stopming other team will tell you nothing because they won't punish your mistakes. In comp you want to use mumble for team communication. Also, get a new hud. Health numbers are pretty much requirement.
From beginning - don't parade yourself in sniper lines, you do that very often. You weren't punished for that now, but you will if you'll continue.
Your uber on red didn't do anything. you want to bodyblock them or ideally get a pyro uber and airblast them. Pyro was roaming a lot, so that wasn't much you could do.
3:52 You went around corner first, non-covered without any support and had to pop. Then you drop down for pyro and you both went chasing frags, that got you killed. It would be great pop if you'd just stayed there and didn't let them get close to sentry, then fall back safely.
4:40 - don't go there. That's just pure overextending. Although at this point it doesn't matter.
6:48 - No. Don't pop out of spawn, your uber was off before you even got to ledge. Heavy can get killed, nobody cares because he will respawn in like 5 seconds anyway. That's why you should buff soldier and demo especially, then heavy and pyro and send them to sentry to take down engie, medic or any other pick. If they get it you have big advantage, if not you can push few seconds later when they respawn (some teams send multiple waves of these suicides for picks).
Don't push cart if you don't have to, there cold be sniper at the end of tunnel. Your soldier got a gun and some other picks, which pretty much won you first point and then match. You didn't have uber at the end of the tunnel, if they'd drop on you - you'd be dead.