As the title suggests, my computer knowledge is average at best, So I am asking for help!

I am a WoW player, and I currently play it on a laptop. But I also edit hours upon hours of video footage. I have 100gb on my laptop, but I am reaching the near capacity of that now, and I need to free up some space. I have an Ext Hard drive. I only play WoW at home, but need the videos at work, so putting the videos on the hard drive is not an option.Is there an easy-ish way of putting WoW on the Ext hard drive without completely reinstalling it? I have tried the nooby ways of doing it, but none have worked! I am just too lazy to go through the install and patch process AGAIN!

Any Ideas?