It highlights the Tier 8 sets that can currently be found in the datafiles, which we've seen before but not in such a clear and simple video, with nice and (generally) neutral lighting. Death Knights, Hunters, Rogues, Mages, Warlocks, and Priests are highlighted, in that order. The last few classes don't have any skins (or hints of skins) buried in the game yet, so we'll need to wait awhile to see those. Out of the ones we can see, I'm not really sure which set is my favorite. They're all pretty cool and fit the class decently enough, except for possibly Hunters which is still cool but looks a lot like a Plate set for some reason. The Priest set is pretty amazing, so I'm definitely looking forward to getting my hands on it eventually.
If you're in a position to do so, I really recommend bopping over to YouTube and watching the video in HD, or even downloading the full thing via Rapidshare. The standard quality YouTube stream just doesn't cut it as far as making out the little details.
There's no sound or music in the video, which may or may not be a blessing. If you just don't feel right watching it without the wildly inappropriate (for the subject) music that plagues most WoW videos, you can just follow this Songza link and play that while you're watching the video. It'll be just like the real thing!
Patch 3.1 brings us Ulduar, dual specs, significant changes to all the classes, and more! We've got you covered from top to bottom with our Guide to Patch 3.1.