I only watched the first clip. Send me a message if you want me to translate the others (if they are different).
Please ignore the sanctimonious liberal imbecile below who said, implicitly, that the translation was racist.
I speak isiZulu.
The translation is inferior, but correct. amaBhunu (not amaBhulu) means whites, specifically Afrikaner whites. It comes from the word the Afrikaners have for themselves - Boer, which means farmer.
Mkhonto we Sizwe (Mk) means The Spear of the Nation which was the military wing of the ANC.
The song means, in a non-literal translation, "Travel safely warriors. We have committed ourselves to killing the farmers/whites. etc" or, more accurately in the Zulu idiom "We have sworn to kill them. Now happy hunting guys".
Please trust me that this is the most accurate translation you will ever find. I speak isiZulu and I lived with (WITH, not "amongst") Zulus. There is absolutely no ambiguity WHATSOEVER in that song. it has one meaning, and one meaning only, in the isiZulu language idiom.