It was definitely the director that needed the firing. Whoever wrote the whole narrator copy got it wrong. They were talking about "British East Africa" and "SE Africa" in the narration and then they would mention Namibia.
What really happened: They had two shoots in the can, one for Zambia, one for Namibia. At a later date they tried to make a single episode from already filmed material that already had narrator's copy done up. Some complete ignoramus at an editing studio tried to knit the two episode segments together into one and got all the facts backwards and confused at an epic level. They even created content like the graphics discussed/depicted for the wrong countries.
Hilarious.