Ah - you've been there too?

(Two years there in the 1960's teaching automechanics when Venezuela was a functioning democracy. It's sad to see what Venezuela is today).
In Venezuela in the era of Chavez (when this happened), it's likely that everyone on the site was a political appointee, no relevant expertise, with the assumed project manager having little control over anyone. Recipe for disaster. Look at that truck waiting to come up the hill, blocking the path of the downhill haul. Total idiocy.
Per the comments to the vid, that heavy-haul contractor is world class but it seems that the downhill slope was covered with gravel like marbles, that turned the trailer into a roller skate. I don't see why the contract hauler didn't refuse to move until that steep slope was paved, for some traction. Or else use a couple of D-11 bulldozers as anchors behind the trailer instead of that useless light truck.
All the comments to the video are worth reading. Several posters have relevant experience with similar hauling.
As always, human error.