AND OR
Use AND to seach for a result that must contain both words, use OR to get the results that contains one of the search words.

3 or less
When your search result contains 3 or less characters no result is shown. E.g. search for BUT, results with the word BUT will not be searched for. But the word BUTTER will be returnd.

More then half
When your search string is found in more the half of the movie database, no result is shown.