That. +1
I come from old school MMO era. Everquest - good luck finding proper kill videos that weren't complete trash or weren't swamped with a dozen player characters swamping the screen.
You had to do a fight to learn a fight.
Just do it.
Keep doing it.
Eventually you learn it.
Once you learn it you improve the fight, you access shortcuts once you reach phases faster. You make the fight yours.
Lots of people don't have the time to do this anymore. I sure don't. I used to, but now...not sure.
So instead you use kill videos to skip 12-15 hours of wipes and learning and get into a particular strat to kill the boss. It's a shortcut. It doesn't breed better players however. It can over long periods of time, but it won't off the bat.