My first impression of the trailer wasn't really a good one. I felt like it didn't really tell me anything. It just showed a bunch of pictures and random clips. I kept on waiting for the trailer to show me a reason why I should watch the movie, but... nothing. I'm sure part of the reason for this is because it's based on a book, which will automatically draw people in, but still. I felt like the trailer should have showed me more of a reason to watch the movie.
Here's where I started to make the connection between movie trailers and (what else?) books. It is absolutely essential that you draw readers into your book. This should happen in the first few pages or at least the first chapter. The first chapter has to unveil a reason for reading the book, whether it be to find out what happens next or because the characters are awesome.
Now there's also the problem of giving too much away in the first chapter. Just like the movie trailer for Fly Away Home did. I remember one time I was over at someone's house and we were going through movies to watch on someone's TV or something, and they had trailers we could watch. Since Fly Away Home is an awesome movie, we watched the trailer. After, everyone joked that we didn't need to watch the movie because it had basically given everything away.
Obviously, you don't want to do that either. I guess most authors don't give EVERYTHING away in the first chapter, but I think this could also count for doing an entire first chapter on backstory. What's wrong with going through the entire movie in the trailer from start to finish is you've left nothing for the watcher to figure out, which is a lot of the fun of watching a movie. Or reading a book. You want to let your readers figure stuff out, make them use their brains. It is a lot more fun, and makes a book way better in my opinion.
Now... looking at a completely different trailer... um, Despicable Me (it's the first one I thought of)...
This trailer gives a bunch of reasons for watching the movie... the characters, the comedy, to see what's going to happen with Gru and the little girls. It also doesn't give away everything that happens in the movie, like the Fly Away Home trailer did.
So like trailers, books need to give the reader a reason to be there, a motivation for reading the book. This motivation will differ from genre to genre and from book to book, but I think it needs to be there. Maybe the cast of characters is why we should stick around. Maybe the gut-twisting suspense. Maybe the romance. Maybe, just simply, to see what happens next. But there has to be a reason for the reader to be there, otherwise they're just going to put the book down.
What makes you keep reading a book? What spikes your interest in the first chapter? What in a movie trailer makes you want to watch the movie?