The nature of the predicament is not valid, because the game has not been launched, and this is obviusly one way to gather the atention to this particular product. It is interesting to ask yourself "are these enemies the real hard ones, or just the regular horde?", "How many diferent ways can i think of to defeat these enemies?", "How much will the enviroment play the role of assisting my game?", and so on. The idea is to create espectations regarding all these ideas you can generate by seeing so few of this new enemies to the series. They dont show anything further than a couple of guns, the use of powers to disable and great graphics, but nothing "escential" to the game. Remember the story? It is the best this game will offer, and that's the best secret they can keep until the game is released. So NO, they are not doing us the favor of "discovering" the game, they just wants us to get our brains blown by how this game will surprise us, regarding this exciting trailers.