'A corporate movie is your elevator pitch'
Mutual trust is very important for a good relationship with your client. This is accomplished with openness: Show them what you stand for.
With a corporate movie, you are sure that all important aspects of your business are discussed. Nothing is forgotten. The movies shows your client why he should choose for you.
A corporate movie is your elevator pitch. It doesn't only tell the your story, it is showing it! That will strengthen your persuasion. After all, seeing is believing.