This video shows hardly anything at all and is another pointless display from the Press Beta. So far only the Yogscast have been doing anything good. I almost didn't link it in the end.
What it does show is how the World PVP aka Mists will work. Showing what looks like 3 idententical fortress maps and another map which looks like a middle ground.
Its good to see 3 sides in world PvP, this is really the only way to balance something. Because if one side becomes domanant, the other two can work together to take them down.
Here is the video: