First thing, he does this frame by frame, so you need to freeze frame every single instance of the light.
For achieving the light paint he just keys it. Number of different methods could be used to key. First probably a quick mask around the freeze frame of the light. Then for pure bright white lightes, the effect Key > Luma Matte. He sets that to "key out darker" then sets the threshold to a high number like 250. After that I think he adds a glow effect.
Where he had the light bulb on the posts, that's achieved by adjusting the opacity and just adding a color effect to it.
Johnny Cuevas, Editor
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.