Quoted from the video description:
“WoW Power Leveling Human Holy Paladin 15-21 Redridge (Part 2)
NO Heirlooms, NO dungeons, ONLY quests.
About This Playlist:
Power leveling is the term used to describe the process of leveling a character as rapidly as possible with the least amount of play time.
This is sort of a personal challenge to see how fast I can do this. I chose Holy Pally and Human because I thought Holy Pally would be fairly slow and thus more of a challenge, and I don’t have any high-level Alliance that I leveled normally so I don’t already know the quests (I mostly played Horde before now, other than a few Alliance and the free 90 I got with WoD which I never play).”