The phrase "to see the trailer" means to watch a short video preview that shows scenes from a movie or TV show to get a sense of what it will be like. Full definition
I remember first seeing a trailer for the game months ago and being very excited for the title, so I jumped at the chance to review the game. (gamersinbeta.com)
That's like Saying i've seen a trailer of a film. (n4g.com)
When I first saw the trailer for Get Out, I thought it was going to be another stupid low - budget horror movie. (timeout.com)