In case anyone is interested in buying a DVD of Song Of The South, it's on sale for $8 or thereabouts at efilmic.com. You have to be a member (free) in order to buy it. Which means you give them your e-mail address. Maybe this is the way they get around the restriction for sales. The company is in Canada. Trust Canada to get things right.
efilmic is a good site on it's own, with very low prices on classic films on DVD.