But actually, I am beginning to wonder if they actually develop (which would require an additional stop or at least fixing stage), or simply throw developer or strong selenium toner onto a "previously-developed-but-bleached-back" piece of photo paper... If they developed it the first time, the developer would likely give a slower response and initially a more blotchy result (until full development). Well, at least with FB, but this is probably RC.
If they pre-developed and pre-bleached it, the additional advantage would be that you had an image not much susceptible to light, you could almost do the re-developing in broad daylight (well... certainly no issue with the kind of lighting you see in this video).
Anyway, the light bulbs in the end seem genuine enough dark room bulb with their orange-green color... so it may have been a first time development.