I've noticed that my glowlights shake to one another. I thought maybe they would be spawning but from what I can tell, these are males. In the video they are in the center. I didn't want to get to close and have them stop.
That's just normal group behavior. It looks like they're showing off to each other, AKA sparring. It's normal behavior in tetras. My three *female* black phantom tetras do it. Females rarely do that in my experience! lol