South Africa was not an example of reverse racism, reverse racism is a made up term.
Older definitions of racism do not include an important aspect of racism, it is not simply disliking or feeling superiority to another group, it is taking that attitude and ascribing power to it. Hence when the KKK marches, it's yawn-worthy as they no longer wield the power they once held. So what institutions do African Americans control that give them power to discriminate against other groups racially?
And to explain white privilege, white privilege is pointing out that American society is geared and designed to the benefit of White Americans. For instance, when it comes to school standards, there are often demands that standards be increased or unchanged when comparing students to African American and Latino students (arguing that they must not be held back), but then arguing to slow things down due to stress when compared to Asian students (arguing that it is too competitive). In both cases, the system is catering to the White majority.
Another great example is right-hand privilege. Most people in the world are right-handed, thus products and facilities are designed to cater to a right-handed populous.
Yet they take the most in federal dollars per capita.