I remember hearing my physics teacher mumble something about how it's not an actual force but that was over 12 years ago. In the meantime nobody had a problem using the term and I'd expect university physics to have a thing or two to say about it if there were a problem. This is centrifugal force overcoming the force of the magnetism. Not terminal velocity. Terminal velocity is gravitational attraction vs. air resistance, which means the object has to be moving towards the gravity source, which is down towards the Earth. What's being demonstrated in this video is rotational speed in the horizontal plane perpendicular to the force of gravity, resulting in centrifugal vs. centripetal forces that overcome the magnetic attraction of each individual magnet to each other, until the structure fails. Hence, aka Kaboom..