Here's an intersection near my place:
This is at night, about 20 minutes ago. Back to basics in Quartz Composer. Top level:
Render in Image is piling up images from the stuff contained within it, according to how those things display colour. There's also a white background, as the image coming through is a few colours and as literally nothing as you can express on a computer. Inside there:
Video Input is split, one path removes the colour and ups the contrast to near black-and-whiteness. The black goes to alpha, which is transparency. That masks the plain video so the only things that poke through are bright chunks of the image. The Blending setting of the Billboard is set to Over, so images it produces are drawn on top of previous ones. The Blending setting of the Sprite is set to Add: a smidge of really dark nearly transparent colour eventually adds up to white, producing the fade. Might have to up the Sprite colour value a little there... It's another approach to get at this, and much less of a strain on the processor.