There is a carrousel and a child riding it. For some reason the child has a bar magnet in one hand and a charged ball in the other (he holds it with a plastic glove because he is a smart kid and doesn’t want the charge to go to ground).
If we put a magnetometer in the center of the carrousell we can measure the magetic potential made by these objects.
We would always measure (even if the carrousel is stopped) the potential created by the bar magnet, this is analogous to the B_dip, seen in the video.
If the carrousel is moving then we would have a charged ball moving relative to the magnetometer, that is a current and that also creates a magnetic field, that would be analogous to the B_orb seen in the lesson.
If we had more children with more charged balls (charged some positive and some negative) they could pass them around in the carrousell to each other throwing them, at some points the flying balls would come really close to the magnetometer in the center, if the number of positive balls in the center at one moment is not equal to the number of negative ones, that would also create a noticeable potential for the magnetometer and thats somehow analogous to the B_fermi