Short selling is a way that investors can profit from (borrowing, and then) selling shares and then buying them back later. The idea is to first sell high and then buy back at a lower price, thereby making a profit. But some aspects of this well accepted process have been causing controversy, especially for those companies that become the target of short selling.
This documentary focuses in particular on naked short selling, i.e. where an investor sells shares that they do not have. It is an interesting little documentary, and it benefits greatly from the input of Jim Chanos - a hedge fund manager who has become famous for his pessimistic views, and correctly predicting the Enron collapse.