Damnit I couldn't help it but to watch it, even though I didn't want to know any spoilers, no matter how insignificant. They revealed much more than I'd like to have known, I would just be content with part 2 about combat and part 3 about exploration and skipped part 1 about the characters and content and part 4 about the story. They could just have given us part 2 and 3 and said "we also have some really cool stuff coming up in terms of choices and the story which you want to experience all first hand" or something.
Oh well as CapnKill said it's not ruining the game, but I really could've done without much of the story-specific info
On another note combat looks AWESOME and so does heavy weapons