They should watch the films before commenting. I do not think that those are racist comments, nor that they are racist themselves. They are white centric. There is nothing wrong with that either.
Regarding the films about slavery, they are very important in the sense that people actually lived and experienced that existence. All races have the scars of slavery. It is not just a black story.
The stories are very powerful reminders that we need to treat each other better as brother humans. No one should at the wrong end of a whip.