Tricky devils, HBO.
Managing to get us excited without not actually giving us new footage--a tease for sure, but perhaps it's the message that's more interesting here. Narrated through the many eyes of Bran's raven (the one that shows up in his "dreams"), it appears that GoT is trying to make some sort of ideological statement--that what's happening in 2013 isn't that dissimilar to a number of fictional realms fighting internally, but really fighting against a very real external enemy. Apocalyptic--like the theme of everything nowadays--but to be fair, they did warn us once or twice about the impending threat of winter.
Season three begins on March 31st. If you don't dig spoilers, I'd highly suggest not reading the YouTube comments on this one.