Master Tamer daily quests are pretty great for leveling: if you can beat the tamer with 1-2 high level pets, then you can include a lowbie who will get a rather large xp boost. For example you can basically solo Farmer Nishi with a high level Magical Crawdad (or possibly a crab, in theory it should be similar but the heals are weaker). The tamer in Hellfire Peninsula has all mechs, and is beatable with a single high level elemental, etc. It takes 2 fights in Dragonblight to get my lowbies up to lvl 6 as per the video you linked, then they usually survive one round vs most tamer pets. In that situation they get 1-2k xp from a tamer fight, depending on the level difference. Also, it's risky, but if you manage to let the high level pet die, it's even better as the lowbies don't have to share the xp reward. I don't recommend this unless the lowbie is within 5 levels of the pet you're fighting, however.