Most movie trailers are mostly advertisements for a film, and while they are well edited, they are often just teasers composed of alot of short clips. Some trailers, though, are small films in themselves. Two such trailers are this one, for the movie, Comedian.
And this one, for the film, Somewhere.
Both of these can easily stand alone as things that can be watched in themselves.
You can find them here (Comedian Movie Trailer – YouTube) and here (Somewhere Movie Trailer Official (HD) – YouTube).
Smart People I Know 
These are both great.