If you’re doing something similar to the two paired hemispheres in the second video, I just used a blueprint actor with a single mesh object (with a flat slice subtracted from the middle, then another smaller sphere subtracted to hollow it out), and a single point light right in the middle parented to the mesh, with a source radius greater than zero to make soft shadows from the light projected through the opening.
I only used four rect lights in that scene, each in front of the four tall black rectangles (two in the starting area, and two in the later area with the mirrors), that emit the intermittent flashing light.