Most movie trailers are garbage. They give away to much of the plot (often the plot of the entire movie), show the best parts, reveal a twist, etc.
But here is an example of an excellent movie trailer:
Everything about this trailer is perfect. In fact, the trailer itself works as its own little piece of flash fiction. It has its own thematic subversion (what appears to be a happy family inside a home at the beginning turns out to be something else entirely), foreshadowing (Mary Elizabeth Winstead’s reaction during the scene where John Goodman’s character is ‘dancing’ at the jukebox), mystery (what’s causing the earth tremors?), danger (the reveal of the pistol), and cliff-hanger ending. The soundtrack, too, is perfect in both lyrics and in the way the song ‘breaks down’ in the same way the picturesque story does as the trailer goes on.
I wish more industry people were as skilled at making movie trailers as the people who made this trailer are.