Holy wow, I'm stunned by how many plot spoilers and visual giveaways EA have managed to cram into their Dead Space launch trailer. Half the game seems to show up in this two minute edit-splatter. I'd suggest you only watch this if you have have zero intention of playing this (rather good) ultra-violent space shooter.
The reason I know how spoilery it is, of course, is because I've played the game in question. My review is in the next issue of the best PC gaming magazine there has ever been: PC Gamer UK. It has their Fallout 3 review in there too. The magazine is out on 23rd October, and Dead Space comes out on the 20th of October on PC.