Tall construction site material handling slide - GIF

[Frank S]

Maybe some possible answers.
Consider. many parts around the world have small steep treacherous winding narrow roads to get from the top to the bottom of a mountain or plateau and vice versa.
If this were the case a truck could deliver from wherever to the edge of the plateau or there could even be a mine or quarry up there. the materials are needed in the valley below. the most efficient and safest way to deliver them possibly is the chute even if only by small quantities at a time. These tubs appear to be lightweight and stackable, for all we know they may have thousands of them available for continuous delivery. The number of cubic meters of material which could be sent down the chute would far exceed the amount a single loaded truck could haul, descending, dump and climb back the many kilometers of road during the same amount of time.
The tubs could be transported back up by a small vehicle or very possibly from cable car system we can't see in the video
Another possibility. They could be doing this as a conservation project, judging by the gridwork of concrete stringers filled with riprap they may be covering it from bottom to top with the material in the tubs.