Interesting and somewhat more quantitative take on this here: http://www.geforce.com/Optimize/Guides/the-elder-scrolls-v-skyrim-tweak-guide (jump to the "FXAA & Water" section; source is Nvidia, so it's geared towards their stuff, but it applies to AMD as well) As with so many things, there are tradeoffs, and the cost/value of those tradeoffs will vary from person to person. Personally, in the middle of the action and at high resolution I'm hard-pressed to notice a difference between MSAA, FXAA, and nothing. That said, I always turn one of them on.

At the end of the video, at the pause between "to find the real story" and "stay tuned", all I could think of for one brief moment was that a website plug would be popping up any second. Ah, progress.