From what I’ve been told, this particular Star Wars trailer, is a teaser rather than any means of spoiling the movie, it is basically what a trailer should be. Nevertheless I know better than to watch any footage from a movie I desperately want to watch.
As the years have gone by, trailers have become more than just a taste of what to expect, but rather a demo of what will happen in the movie, sometimes even giving us the whole plot in just 2 minutes, with the best jokes, action sequences or even twists included. Even people in the business hate that this is happening, but producers and Hollywood studios just want to get as much publicity as possible, albeit it ruins the movie.
I like to be kept in the dark, knowing nothing about a movie before I watch it. Usually knowing members of the cast & crew will suffice, I can use that to determine what to expect and whether it’s worth watching or not. If that isn’t enough a two sentence summary on IMDB should do the job (however I prefer not to do that, as it sometimes gives away the prologue~first 20 minutes or so)