> An optical spectrum of what appears to have been a ball lightning event was published in January 2014 and included a video at high frame rate
https://www.youtube.com/watch?v=1bBNeyrMOJE
I think what that sentence is saying is that we don't know how to reproduce it in a lab. We don't know what exactly is happening in the real world that is causing us to perceive this. It could be an illusion I guess, but I think it's undisputed it's a real phenomenon.