This is the end of the fail version of FFXIV 1.0. A new version (Final Fantasy XIV: A Realm Reborn) is on Alpha right now, it will release in PC and PS3 around March or April.
To give a little context: just gonna repost what I messaged to a friend who wanted to know WTF was going on in the vid:
in XIV 1.0 theres an Empire, which is a nation of anti-deity fanatics (Garlean Empire), one crazy general (Nael Van Darnus) who leads them summons to earth this meteor to kill the deity worshiping nations who oppose the empire (everyone else, basically). at the end of 1.0 you kill this general (Instanced content) but it's too late, the meteor is still coming. Gandalf like guy is named Louisoux (a recurring character) tells you that your only hope of stopping it is to pray to the 12 gods (deities) in hopes they will save you. so everyone did for like 1 month leading up to the end, and there were quests/events focused around that.
in the video: there was this final confrontation between the good guys (Eorzeans) and empire before the meteor hit. a last stand of sorts. right before the meteor hits, turns out it was a prison for bahamut who then proceeds to nuke everything basically. Louisoux tries to summon the 12 gods (the blue symbols) and reseal bahamut using the accumulated power of prayer, but this fails. using the last bit of prayer power he transports those good guys on the battlefield to safety/or to 5 years in the future (Louisoux guy is closely aligned with the deity of time and space, Althyk - The Keeper). the world is basically left in ruins with survivors in the cities, but a lot of people died. as for what happens next... well, we'll see! ~FIN~
Something more, Garlean Empire is not only at war with Eorzea, they are too fighting Dravanian (Dragons empire, as you can see in 1.0 opening video) and in the end, to destroy Eorzeans they released their greater enemy, Dravanians God: Bahamut.