In a WoW forum there is a step-by-step make you own WoW movie post. The post is great for those who want to make movies, but it also tells n00bs in that field - like me - how you can record what happens in the game.
Fraps (http://www.fraps.com)I think this is brilliant. Now, storing all the material you need for research will crowd a regular harddisk in no time, but thats why the goddes made separate harddisks. I haven't had time to try this out yet, and won't be able to until the weekend, but I will be back with more information once I know. I also don't know how much this may make the computer lag. It may be time for a dedicated game research machine set up somewhere convenient and comfortable.
Fraps is a good video capture program, with some nice features. The free version is limited to only 30 seconds of recording (including sound) but the full version is purchasable at their website, enabling unlimited recording.
Gamecam, like Fraps, is a nifty little capturing program available in two doses, normal and "lite". I'd suggest downloading the lite version, as you get rid of all the pointless bulk that the normal one has. The free version includes quality adjustments and limitless recording, but with no sound and hindered configuration. Setting up takes a bit more effort, too, but a guide on the site explains it easily.
I tried both these out, and found that gamecam was more performance friendly framerate wise, as it kept my FPS intact. Fraps, i think requires a more powerfull computer. Correct me if I'm wrong there.
I wonder if the family will sell my clothes and books and rent out my space in the home if I start another year-long period of game-recording from a work-based machine...