Expectations of a movie trailer

I went in to Sutton Town Centre and did a 30 people survey asking what makes a good trailer. The sort of questions that were asked were 'How long should a trailer be?', 'What should be included in a trailer?' 'Should a lot about the movie be in the trailer?' Overall, I received a variety of feedback, but most people said that they prefer movie trailer to be shorter that 2 minutes because they find that most movie trailers give out way to much information than they should.