I have mild Asperger's and some type of attention disorder(s?). I don't know if that applies to you.
SKIP the video's. Many are bad. maybe they need to be slower? IF they don't work, they don't work.
I'd suggest studying Saint Sheldon.
https://www.sheldonbrown.com/repairs.html

Then again, maybe this isn't for you. I'm useless when it comes to Arts & Literature.
Take your time.