the short film that inspired District 9

 
Before Neill Blomkamp made District 9, he made a short film (a little over five minutes long... if you don't count the credits) called Alive in Joberg. 

If you haven't seen District 9, you may want to be wary of potential spoilers, though I seriously doubt seeing the short film on which District 9 was based is going to lessen your enjoyment of the feature-length version. If anything, I think it's more likely to enhance it.