In Play, page-82

So you understand what shorting is right? (In case you don't it's people borrowing stocks to sell and then rebuying them at lower prices to pay off their stock debt - E.G. if you think Flexi is going to $2 you short it now and rebuy at $2 and make 33c a share).

So typically less shorts means less negative sentiment. However if there are large numbers of shorts it means the Share price could go on a run as shorts are forced to buy to avoid losses

If you have any more questions (I know this is brief) please post them.