Not to say it isn't racist for a white person to use the word "nigger"--it certainly is--but I do think Terry wasn't talking about Africans most of the time--or even about human beings.
How many black people actually work for the CIA? When you imagine a stereotypical CIA agent, are they black? He often alluded to these "CIA niggers" being space aliens; he believed they glow in the dark.
I'm pretty sure when Terry said "niggers" he really meant "subversive aliens" and didn't mean to insult African people.
If you watch that video, he says "hey nigger" in a pretty friendly way. I don't think he meant it as an insult; he probably just didn't understand that this is not an acceptable way for a white human to greet a black human.