That last video, at about 3:55, shows the ring as a bunch of red balls surrounded by a bunch of blue balls. All the balls seem randomly distributed, but a smal

That last video, at about 3:55, shows the ring as a bunch of red balls surrounded by a bunch of blue balls. All the balls seem randomly distributed, but a small subset are colored red. I wonder what makes those balls different? There doesn't seem to be anything unusual about their arrangement, other than they chose to color them red.