It's pretty impressive to survive 30 or 40 waves of enemies in the Proving Grounds, a World of Warcraft scenario where you can test your raiding abilities by facing enemies that get stronger with each wave. So the fact that frost mage Akuyama reached wave 138 and set a new world record is incredible.
You can watch the last ten waves in his clip. Beating 30 waves grants you an achievement, so this should be worth at least an epic mount. Also, really smart use of Icy Veins.