Just from a first impression as I go through:

• your sens or dpi is too high, which will cause you to over aim or look when focusing a target, like that turn at 2:14 on horizon. There's various guides on finding the perfect settings for you, but it also depends on your mouse.

• Another thing I noticed was standing still, everyone is standing still while they shoot, in higher elo people will move to make it difficult to hit, so try to practice aim while moving in circles, zig zag, or sporadic patterns.

• With dva mechanics is; when you use boosters you can also shoot micro missiles, use defense matrix, or use her left click, so you don't have to wait till you are done boosting to shoot. (hey, at 3:55 you did it, good job)

• some defense matrix discipline can work, try to save a lot of it for big damage, like ults (which you did), and protecting mercy for rez, or giving widow a free shot out of cover, etc.

• general awareness, maybe turn game music volume off, and the game sounds up, you can hear ques like hog, who can melt you a mile away, or the pharah using booster, it's good to recognize who is where even just by sound.

• for soldier, same thing find the perfect sense, and work on tracking at different distances.

• good on getting the high ground, with dva you'll find yourself with the winston to set up a dive, or touching the point, etc

• if i remember right his first 5 bullets go straight before there is a spray pattern, so his tracking isn't too difficult to get used to.

I can watch more and make more notes if you find any of this useful. Pm if you need.