Blackfish

This was a documentary on the cruelties of orca whales kept in captivity, specifically at Sea World and Marine Land. I found it very informative and really shed some light on an issue that I really didn't know existed. The director did a great job of getting multiple perspectives on the issue, with lots of interviews and archived footage of events that actually happened. The thing I didn't like is that as it went on it started to get slightly preachy with less factual arguments and more biased beliefs. They also could have used more people on the other side of the argument, instead of just using old interviews taken out of context.
With all of this said though, I still believe it was an effective argument and it certainly made me want to become active in freeing the whales and taking down companies who treat animals cruelly.