One could learn a lot about specific cultures or countries by watching movies from that specific culture or country.
For instance, in our country, the audience can learn about early racial prejudice by watching a movie such as D. W. Griffith's 1915 Birth of a Nation. A movie filmed post-Civil War but during nation-wide segregation laws. Most important African American roles in Birth are played by Caucasians with "black face" paint, while the roles of slaves or servants are depicted by actual African Americans. Someone from another country could look upon this movie and wonder about American's ideas of African American. Not only are most African American roles in Birth are played by Caucasians, but also all of the African Americans in the movie are shown as ignorant and immoral. Showing how our nation and Hollywood felt about African Americans at the time.
Even beyond the United States one could learn about a specific country or culture. Another example would be anything made by the Monty Python boys, including movies as well as television. Monty Python is a comedy troupe based in England that started during the sixties. They are famously known for Monty Python's Flying Circus, first directed by Ian McNaughton in 1969, and Monty Python and the Holy Grail, directed by Terry Gilliam and Terry Jones in 1975, amongst many others. Monty Python is the best known symbol of British humor, which is usually known to be rather dry and very silly. Most Americans believe British people to be very snotty, not friendly, and overall very stuffy. Monty Python, in some fashions, works on this stereotype, usually blowing it out of proportion. The Pythons poke fun at everything from the Queen Mother to the Pope to ideas of chivalry. Monty Python gives audiences outside the UK a brief look at their lives and how British people make fun of themselves.
Audiences can compare and relate racism and comedians in our culture with the equivalents in other cultures and vice versa.