Don't know if you're looking for tips to improve or not but I'll try and help you out anyway.
You should really keep that crosshair up at head level. Instead of having to make unnecessary movements to adjust your aim when you spot an enemy, you can just get used to keeping your aim at their heads or even torsos. Of course, this varies for different maps and different surfaces but it all comes with experience. Really valuable thing to learn early on.
The last thing I can comment on from this video is the sensitivity. It's not insanely high, but it is relatively high. If you look at some pro player's settings you'll see that their sensitivities are usually quite low. That doesn't mean that yours should be as low as theirs, since they do have a shit ton of space to move around, but lowering it until you're comfortable would help you out by a huge margin. At first it will feel wonky as hell but with a couple of deathmatch games you'd be all good. Tracing people around should become much easier and flicks should be more precise.
This is optional as it's 100% personal preference, but you can try and play with your resolution. Most of the higher ranked players play on stretched resolutions like 1280x720 for example. You could go ahead and try out some for yourself at one point but that's just for bringing out the best of your aim, which isn't required at your current skill level.
Also, I suggest not playing competitive until you've gotten used to how most maps and weapons work in deathmatch and casual. Suppose you'd prefer getting ranked higher than silver 1 or 2 ¯\_(ツ)_/¯
