The point is, there are very little tutorials on Java regarding L2j, whereas you can find millions of books and tutorials on the subject of Java as a whole, and tbh if Matim is willing to spend his time making them, why cover shit other people have already covered? TheNewBoston has a lot of java tutorials that are very good quality and are produced well.
Matim's tutorials need to have a voice-over on them, if he isn't willing to do that then it is useless to even make them as most people will not follow him typing on the screen and/or making the tutorial as a topic, they are too hard to follow.