It always seems like i am behind TwilightPrinze, but here is my two cents. First of all as Prology said though your banner and avatar aren't bad I would also recommend maybe trying to update them and make sure you are using catchy titles for your videos. Think of how many people are making the same type of video as you, what are you going to do to make yours stand out?
Secondly make sure to adjust your audio volume, as your commentary does come across very quiet in some videos, especially your recent WaW Zombies video, if your unsure how this might sound, I do recommend making a test recording and listening back to it beforehand. I forget to do this sometimes and kick myself every time when I have to redo a video because I can't hear my voice.
Thirdly, cover some more recent games, I am not meaning to sound harsh but think of your audience - why would they watch your 20 minute video on Waw Zombies when they could watch zombies mode of Black Ops 3 for example?
Fourth, stay active on your channel - By that I mean have some form of schedule, keep uploading videos (this doesn't have to be everyday it can be once a week if thats your thing) and make sure to take the time to thank everybody for commenting on your video / giving feedback. I know this can look / feel slightly repetitive especially if you have 20 people commenting things such as "nice video" , but a quick comment to them just saying something along the lines of "thanks for taking the time to comment, I really appreciate it" can do wonders in securing repeat viewers and getting your channel noticed.
Fifth don't be afraid to advertise your content via social media - There is even a segment on Freedom where you can do it if you wanted to start off small, just make sure your trying your best to get noticed.
Anyway, I think I have made you read enough of my prattle so I am going to leave it there. Hope my tips help you and if you ever want to talk things over more fully then please don't hesitate to let me know. Keep up the hard work