First 30 seconds are the most important.
First, you had the video playing quickly while it went from low volume to loud sniper shots. You drag your words on and it seems like you are trying to be as low as possible so someone in your house can't hear you but loud enough so we can.
I'd recommend that you slice the best scenes and put them together or take 3-4 different games and show streaks until you die with maybe 2-3 more kills then transition to a new match.
If you are doing commentary, it might be a good thing to record yourself while playing and get your reactions then if you want to have full matches. If not, slice them clips up.
Also, the first 9 or seconds you are silent, by about the first 2-3 seconds I should "Hey! What's up, this is ______ with my first ever commentary bring you one of games on _____"
Your first commentary, along with your next 10 will not be good; very few are good. These people you see with large subscribers, they started out small and probably not the best either and learned. You need to be charismatic. That's what draws people to watch your videos more.
I'm guessing you are like me, quiet, it shows in your speech. If you do plan on making some of these, a good idea to start out with is maybe get some friends who have mics and connect them to your computer and record your reactions while playing, with friends you will most likely say things you normally don't and be more exciting. "Holy shit mate, you see that! That bastard threw a knife at my dick".