New Moon Trailer is not what it seems......

Okay so I've been reading people's comments about the trailer. A lot of fans are saying that the trailer wasn't going by the book. After watching the trailer continuously, about 100 times today! LoL I completely disagree. If you watch the trailer carefully you will notice that when Bella is talking to Laurent in the meadow, she is wearing a backpack. And then Laurent hears the growling. And in the scene when Jacob transforms into a werewolf, she isn't wearing a backpack. So clearly it isn't the same scene they just combined the two scenes together for the trailer. They probably aimed for fooling everyone so that when we all watch the movie we would be shocked that they did go by the book after all!