Waaaaaaaaay too many people hung up in this thread about silly points.
"Just pull out melee weapons and finish them off quicker!"
Uhh, it's not about speed, it's about efficiency. A barbarian in the same situation would take damage which means that he'd eventually have to chug potions or grab a hireling to heal him, or else die of attrition. Taking no damage is the best way to mitigate damage.
"It's in Vale"
Well gee, it's basically a HOW-TO video. It shouldn't matter if it's there, Korthos, or end-game content. Don't get hung up on this little detail when this has been explained in the thread. Reading is your friend!
"Good for soloing, but not for party"
Thank you Team Obvious. Did you happen to read the thread title? He's demonstrating solo tactics. Nothing more, nothing less.