>>265534862
0:28 Another flashbang is pulled. Again, think of what you're doing with the flashbang. You see that Emisune has moved up, and that there is no more gunfire. Flashing into B now would cause Emisune to be blinded for no reason because B is clear for now, and they are probably in the middle of B. If your intention was to flash over B walls, you've pulled too early and locked yourself from firing back in case the situation changes. 
0:38 You picked up your gun. But because you've locked yourself to using the flashbang, you're dead meat if someone was on stairs prepared for you.
0:39 Risky flash on stairs that could have blinded you alone. It could work if you were throwing it out of cover, but I wouldn't do that in the open. 
0:41So on aim. When you're aiming around a corner, keep your gun trained at the corner as you expose yourself and move so that if you see someone to kill, you can
shoot them faster while exposing little of yourself. And when holding a position, make sure your gun is pointed at the exact place an enemy would first show up in your field of vision. 
Right now, you have your sights(and using the AK trick for mid range) pointed in the middle of the exit of lower tunnels. I see where you are going with this because you want an equal amount of
coverage between all possible spots you can be shot from. Right now where your sights are, you have to do too much movement to effectively shoot anyone that shows up, which means your accuracy is not guaranteed. 
You should have chosen to either aim at the left side of the tunnel exit where someone from CT spawn would show up first, or try to snipe a head on Catwalk and aim at the ledge. If you aim at the ledge, try to aim normally rather than using the AK sight trick.