A bit late in the games life cycle to be bringing a video out about this IMO

Couldn't watch the video for now, but I'll just say: the number one factor in winning gunfights is internet connection and lag compensation. I've played on two wildly different connections for quite a long time on this game, and I have a DISTINCT advantage with one than the other. On my bad one I'll literally get killed by guns in one bullets, or run behind walls and be shot a full second later. Basically if you're getting into a battle and the other person is talking to the main server before you, if they shoot, they'll have gotten 3 bullets into you before you can even "talk" to the host. It's ridiculous.

I'm guessing you cover the three magical defense techniques, in my opinion, strafing, cover, and dropping. But like I said, when you're dropping but person shooting at you has already killed you while standing, when you're running behind cover but apparently they're already put a lethal amount of bullets in, it really doesn't matter. These are good techniques to win when you have even internet connections, but if you don't have a good internet connection like one of mine, you have to get behind people/ majorly outsmart them.

Dropshot, Jumpshot, Strafe shooting work for me.  But really the key is stay away from areas where you are exposed from multiple sides, and kill as many people from the backs and sides as possible. 

MW3's quick kill times, combined with it's connection issues, combined with the fact the opponent may have quickdraw and a quicker killing weapon without a silencer while you may have a silenced weapon without quickdraw, etc...means you should try to limit head-on, come around the corner at the same time encounters as much as you can.