I noticed throughout that whole video pretty much only PLD takes any damage. It doesn't seem to be a lot of damage either. So it seems the mobs in here don't AoE often if at all, including bosses, cause WAR and MNK are straight up in there.
It also seems that PLD is an awesome tank, holding all the mobs while taking minimal damage. This kind of makes me question how "challenging" this dungeon is. These people don't appear to be struggling at all. Also note that they're getting along fine with their stationary casting and without all their cross class abilities.
Last, I noticed with the food buffs at chimera that PLD has over 4k HP while WAR had over 5k. I know they don't have +HP materia either since AF gear isn't meld-able... So either job stats, AF gear, or both are awesome.