Oh wow, thanks for such thorough feedback!
Certainly, the overall structure of my video could be better. I came up with ~50% of the script in the first few hours and it reflects how my train of though was going. That's where all the ramblings about Doom 2 / favorite monster came from. And then the other half was written as I started making it, so there's that.
Regarding where the music section should have gone - I'm not sure myself. It was the most relaxing topic for me to cover. So naturally I put it right before the end :)
Anyway, you're right - it is my first time. I hope to improve in the future and I'm glad you had fun watching!