Your video quality looks perfectly fine, can't find any problems there.
I think the main improvement you can make is with your commentary. I can tell by listening to you and reading your posts that English is probably not your first language, and there's nothing wrong with that, but it's more a matter of making your commentary more entertaining. Give some variations in your voice level as opposed to something in one tone, and try to give some amusing sidetracks in your commentary (like in one Painkiller episode I watched, you constantly stopped talking when a monster tried to attack you, so say something like "STOP INTERRUPTING DAMNIT!", or something like that) as opposed to merely summarizing what's on-screen, since that's something we can all see. Generally speaking, when people subscribe and watch your videos, they come for you, not your gameplay, so don't be afraid to be a little bit "out there" for entertainment purposes.
Going hand-in-hand with the commentary, you ought to do something with your audio levels. I'm not sure if you're talking silently, or if the mic's silent, or if the game's just really loud, but I can barely hear you. Don't make your voice too loud, obviously, but when the game is as loud as your voice, it creates some problems when the person watching the video can't hear what you're saying. Your mic quality isn't all that great either, so if possible, I would recommend a better mic. Obviously, though, that's a rather large investment for a top-notch mic, so I wouldn't rush that decision.
Other than that, there's nothing much more I can say. A lot of improving your commentary will come with time, but a lot can be done with practice as well. The more you commentate, the more will come naturally, so it might be wise to also put up some post-commentaries (commentaries done after the video is made) just for practice in on-the-spot thinking. If you have to script them that's fine, but if you want to get better, you should move away from scripts and just plan out the general idea of your commentary and then let it flow from there. Doing that will get you a lot of natural practice (if that makes sense) in just going with the flow during your commentary, and once you get used to that, your commentary will be many times better.
