It was a scene during a video (I think a PvP video) meant to make fun of how crappy Hammer of Wrath used to be.
It was a fight in Stromgarde, the enemy had low health and started to run and the Paladin started casting Hammer of Wrath for a very drawn out cast time, then it hit the enemy and didn't kill him and he ran off.
I checked Zalgradis 3, figuring it was him since he had a lot of humour in his videos but it wasn't there, I can't check the other ones just yet as they are very long videos.
A bump is required for this thread. Kept searching for 3 hours due to it bugging the hell out of me to no avail other than this thread popping up over and over again.