Nice YouTube vid on minor chords (simple stuff)

[adamg67]

So, I know this is really simple stuff for a lot of people here, but there are probably also people like me who've finally decided to learn some theory and find it all a bit weird

I've come across things about diatonic harmony before, usually in amongst other learning (for example Scott's Bass Lessons), and just kept thinking, how does this work for all the things I like? They pretty much universally have a minor feel, or they're blues based. I thought I would have another look so went googling and (after quite  a few more vids telling how to do major stuff) found this vid. I know it's using guitar for an example but it seems like the theory will work on anything.