I have a very hard time taking David Duke seriously on a topic like this.
There is some interesting info about the farm attacks on wikipedia, which is probably a better source than this guy.
SA is a place where racial issues are obviously more raw than other places. White farmers have made a lot of claims about these attacks being racially motivated against them.
According to an inquiry into these attacks(that I found on wikipedia), unlike Mr. Duke's claims, only a small portion of farm attacks involved murder and the vast majority did involve theft. In most cases where theft did not occur, there was a reason, such as people coming to help the farmers.
The victims of the attacks are disproportionately white, but the people who own land in SA are also disproportionately white. There is little reason to rob someone who doesn't have anything. Also, it isn't like it is only happening to white people. The report finds that 61% of the victims were white.
So overall this seems like another case of a racist guy looking at a complicated situation and just seeing what he wants to see.
South African farm attacks - Wikipedia, the free encyclopedia