Dang, hard time to do Runescape videos. They died then came out with old school again then died again so you missed the 8 ball by alittle. Also the only thing new you can do is PVP videos unless you make some better videos then idkwhatsrs did. Or have some hella good money making guides. Here are some tips I could give though, but by no means am I like a top rated person so don't take me as the final word.
Tips:
1) I mean Runescape isn't a demanding game at all but I would think out picking up a gaming rig on black Friday or something.
2) Have some type of thumbnail on your videos. When it comes to games that are or have been played out you need to have something that stands out an makes people want to click on your video.
3) Use OBS or something with thats less demanding. Also OBS will allow you to put a face cam , start streaming, put some overlays and also you can record custom areas which would help you as I see in most of your videos we can see the top bar on the private server pop-up.
4)Commentaries will go a long way, I saw in some of your videos it was just music with you talking to people in the game. Also on the ones you did talk your voice was pretty soft , I had to up my volume abit to hear you.
5)Make your channel appeal to the eye more. A few ways you can do this is make some kind of "welcome to my channel" video with a brief explanation of what they should expect if they subscribe. Put your videos in playlist so videos are easier to find if people like a certain type of video series, also this increases the odds of people watching the next video in said playlist.