Well it depends on what you're applying for I suppose. I have never put it on a resume that I remember, but I don't remember everything I've ever done, so who knows.
I'd probably be a bit less specific about it, though, and maybe put it more in a "Related Skills" section. Something about "Situational Awareness," "Multi-tasking," and "Team-based, goal oriented environment." Those are good resume buzz words. Focus on words like that, use fewer Warcraft words (like Restoration Shaman, Art of Ruin, and Azeroth), and just be more vague in general about the video game part of it.
Maybe something like this:
Participated in large-team-based, goal oriented gaming requiring situational awareness and multi-tasking skills. Effective communication, quick learning, patience, and the ability to remain calm under pressure were necessary to be successful.
Don't put dates or any sort of proper nouns, just list it down there with "can type a billion words per minute" or with "I won the prize for Least Likable in my 4th grade class." Whatever section like that that you've got on your resume.
Unless you're applying to be in a raiding guild, of course. Then forget everything I just said!