This video is chapter 6 in my series on special relativity, and it covers the topic of relativistic addition of velocity: aka, how things that are moving relative to one inertial reference frame, which is moving relative to another reference frame, what speed or velocity are those things moving relative to the second frame. We'll show this using the Lorentz transformation of moving worldlines, enacted with a mechanical minkowski diagram, aka mechanical Lorentz transformation, aka spacetime globe.