OK, I've figured it out. But I feel bad giving it all away, so I'll just post a link to the group where I discovered the details: The Light Lounge: Orbs and Globes.

Turns out CaraRose and CLKunst were correct. And it should be noted that Denis (Biskitboy) himself provided the biggest clue: "If you have a look around the groups that I, and other light painters frequent on Flickr you will clearly how this type of work is done."