In high school, I did an extended essay on attitudes towards African-Americans in film during the civil rights movement. I kind of rushed it but this book was my main source - it's really great reading for anyone interested in race, even if you don't know much about film. I didn't find any documentaries so if you ever do find one, please share.
Since you're looking for different forms of media what you may want to find are interviews on YouTube. Spike Lee is a good bet, especially if you can get an interview about Do the Right Thing.