As Fuzzy knows, I play piano.
As my piano teacher has discovered, I am hopeless at putting together top 3/10/100 lists. I don't know. I can't pick just a few over *all* the others. And they're all so different. And it changes over time. ... she's just happy when I pick something to work on.
Here's a couple of questionable music theory videos from some guy ....
Reading sheet music:
YouTube
Introduction to chords:
YouTube
... don't forget to breathe.