The truth and history of slavery is well-told in many better places and forms, that aren't so exploitive, that aren't designed by Italian schlock producers to tittilate a white racist audience.
A good place to start is here:
http://xroads.virginia.edu/~hyper/wpa/wpahome.html
A book that I own and would recommend is this:
http://www.goodreads.com/book/show/369801.The_Slave_s_Narrative
With respect, there's no need to recommend any reading about slavery to me. It's a topic in which I've been interested for a long time. One of my closest friends is a world-renowned expert who has been publishing on the subject for 20 years, and I'm currently researching a piece on American representations of slavery myself.
Why do you assume the audience for GUT would have been either racist or white? I'd have thought it was pretty clearly aimed at a militant black audience.
I prefer to gain an education about slavery from the mouths of those who lived under it; better even learning it from those who heard the stories sitting at their grandparents' knee, than relying on a couple of Italians looking to score some fast dollars.
You're learning about it from people who lived it by watching GUT. All the characters are real, and the directors claim that all the speeches are taken verbatim from their writings. I can't vouch for that in every case, but I have looked into the racist doctor who appears near the end, and it is absolutely true (although I've found no evidence that he was Jewish).
Also, you must agree that GUT accords with the accounts given in (many of) the slave narratives you've read, right? In which case, I assume that your objection is to seeing such events, as opposed to reading about them?