I am one of those people when it comes to dungeons (not extremes and what not). I've tried watching videos and I lose interest about 3 minutes in or I manage to watch it all but I forgot most of it while waiting for 30 minutes for the que.

I also feel it's easier to have a general run down before each boss. Saying "Move left, dodge this, jump right" before each boss is way easier than trying to digest the entire dungeon before hand. Plus giving a quick run down is what everyone else does in every other MMO I've ever played, didn't realize this was even an issue.