I must respectfully disagree with existing answers to this interesting question.
As Keith McClary noted, this object has a larger diameter than most pneumatic capsules. Capsules have reason to be small, both to increase pressure per area on their exposed surface, and so that tubes with wide bends can fit into buildings. According to an archived article from capsu.org, "Most tubes were 2 1/2 inches in diameter, with 3 inch diameter tubes being used where traffic was particularly heavy." What is shown in the video may be a foot in a diameter.
No tube at all is visible here. Rather, the mystery object rides atop a thick, rigid rail, casting a tight shadow upwards which might otherwise be distorted by the light passing through a glass pipe. This rail's hanger therefore has to be offset to avoid fouling the payload. Despite the camera's movement, the hanger visible at the right seems to consist of a single L-shaped element. No tube would be hung in this fashion.
Wikipedia suggests a normal speed of 7.5 to 10 meters per second for pneumatic capsules. The object in the video is moving not much faster than the men walk, or maybe a tenth of a capsule's speed.
The "MATTEL, INC." stock certificate that follows is a good clue that could lead to a precise answer. While Mattel is a toy company, the object is not obviously a toy, though it could be a prototype of one.
The object is used for some kind of transit but as we do not recognize its form, it is probably a purpose-built container of specific dimension, a shuttle borne along the rail by a chain drive or worm drive system.