Look at the half moon then look at the video again, imagine a camera trying to focus on a distant source with a tiny chip in the lens like this (especially near the end when the light angle changes and it appears rounder.)
Looks good but I’m thinking lens refraction of a distant light source. Looks like your seeing imperfections in the lens when trying to focus on a light source. The light source is blurry but the camera will focus on the light hitting the lens and sharpen the image of the inside of the lens. IMO.
Look at the half moon then look at the video again, imagine a camera trying to focus on a distant source with a tiny chip in the lens like this (especially near the end when the light angle changes and it appears rounder.)