I once used the same road from South Africa via Martin's bridge border post. That road is lovely. What I can tell you is that I was travelling at 120km/h and almost ALL cars from the direction of Gaborone passed/overtook me! I am not sure by how what speed is one allowed to exceed the stipulated speed limit. However, as a foreigner, I was not tempted to transgress their traffic laws.
Great Vlog, My Hope is THE Botswana Government Put EMPHASIS on Maintenance Of its Roads By Cutting Grass off the Medians and Side Walks not Forgetting ROAD Markings, Otherwise they ARE Doing A Great Job!! Thank you Sir.