Video on Gygax style campaign (West Marches?)

If you're ever bored, this guy's channel might have some interesting videos and playlists. Anyway, Advanced Dungeons and Dragons by Gary Gygax was brilliant, but also a mess. I have never understood the rules or really the intended style of play. The thing is that I tried like hell to understand stand it and still couldn't. I think this guy description is the best I have heard so far. The d&d game he descibes in the video has also been called "West Marches" style of play I think. You will have to copy and paste the link: https://m.youtube.com/watch?v=slBsxmHs070