The speed with which the system travels is why it is so important to write neatly, and uniformly when addressing envelopes so the system can work smoothly. Not only would that whole system come to a halt, but it would be a massive derailment. Keeping that image in your mind, think about the letters you saw in the video whirring through the automated system, and then throw a binder clip, or a bad address into the mix anything that would cause the system to stop. Have you ever tripped going down the stairs? Hurts, doesn’t it? Now, have you ever tripped while runningdown the stairs? I haven’t (that requires being able to run down stairs which I’m not coordinated enough to do), but one would imagine that the momentum your speed carries with it would make your injuries exponentially worse… or at least you would fall a lot further.
If you haven’t watched the video All Systems at Work on my “ How the Post Office Works“, you may want to take a minute to do this. Many do not understand the intricacies of the system, or how easily they can be tripped up. I think that addressing letters and other types of mail may be considered a dying art ( very broadly speaking).