Those are the average rankings for this movie. The administrators of IMDB seem to think a score of 3.2 is more appropriate, perhaps they believe the positive scores to be garbage and the negative scores to be more legitimate.
If one throws out the 10's and the 1's, the mean comes to 5.1.
Googlevideo has an average ranking of 4.5 stars out of 5.
http://www.imdb.com/ratings_explained
"Weighted Average Ratings
IMDb publishes weighted vote averages rather than raw data averages. Various filters are applied to the raw data in order to eliminate and reduce attempts at 'vote stuffing' by individuals more interested in changing the current rating of a movie than giving their true opinion of it.
The exact methods we use will not be disclosed. This should ensure that the policy remains effective. The result is a more accurate vote average."
I can imagine there being vote stuffers. But I still doubt that the result is a more accurate vote average.