I was shocked that my nieces and nephew had never heard of "Song of the South" so I thought I would buy it for them. I couldn't find it anywhere, so I went to the Disney Store and the person there had never heard of it either. I think that Disney at least in the US would just prefer to pretend they never made the movie.
I believe the last time it was in the theaters was in the mid-1970s (I know I saw it there when I was around 9 or 10).
Check Ebay. I got one (DVD) from England, where they aren't so uptight about racial issues.
Last I looked YouTube had the whole movie. Along with all the great Bugs Bunny cartoons that were banned.
In fact, if Disney didn't get to it, they even had Sunflower from a "Wonderful World of Color" broadcast! I loved seeing her!
I'm sorry, I just looked on You Tube and it's not there.
I got it on E-Bay though. It was a European release.