The loading of a UPS semi might not look like this - at all... In addition to the criteria already mentioned by your parent-post, that need to be considered while loading, stability of the load is another important factor. The system in the video just stacks same-sized packages on top of each other, which is not the best approach. The reality is much more complicated as this. You might also be surprised, that the loading-speed shown is not that much faster than a human can do it.