A "preview trailer" is a short video that gives you a glimpse or sneak peek of a movie or TV show. It is used to build excitement and generate interest by showing some of the most exciting or intriguing parts of the media. Full definition
Not even preview trailers for other movies at the beginning of the disc. (dvdizzy.com)
There was a brief preview trailer finally shown at E3 this year, but we're still mostly in the dark about how systems will work in the game. (nintendotoday.com)
Watch out for a pretty funny sneak peak into the next preview trailer towards the end as well. (thatvideogameblog.com)