@gabe When I learned, we had man pages, and the AT&T papers. Then came O'Reilly, and we finally had books. Then eventually books on websites. Video is good at demonstrating some stuff, but honestly it's a really low bandwidth compared to text, especially considering that linux sysadmin is primarily a text-based world, not a gui one.
Having said that, I keep noticing well-subtitled training videos popping up on LinkedIn, so they are out there.