Be sure to watch the video in high definition -- it's well worth it. Also watch it all the way through. At the end you're shown how to change the color of blood that mobs splatter when hit. Green blood is now my setting of choice, if only because now every mob spills green blood, just like Spock.
As he notes in the video, and as I can attest to, these settings really do slow down your frame rate, so don't play with them during raids. People commonly say that WoW's graphics are eight years old, but that's not true -- the system uses a ton of graphics power when you have the settings turned up. When you do it like this and push them beyond the ultra settings, you'll quickly kill your gameplay experience for a really nice image. So it's fun to play with, but be think about what you're doing before punching in console commands.