A few things I notice in this wondrous little film by "Jean-Michel" making the rounds of the social networks that I wouldn't have noticed before beginning work with Cay on Spider Silk:
There is a spiral scaffold already in place before this spider begins laying down the final capture spiral (the main action here). I know now that that spiral scaffold consists of a silk that is different from the final capture spiral silk. (And, of course--although, I didn't know this "of course" before Spider Silk--the frame lines and radial lines consist of yet another different silk.)
The web isn't really symmetrical. Notice the spider reversing course and making extra passes at the bottom of the web.
When the spider gets back to the center of the web, the hub, it eats the silk that made up the hub.
If you'd like to see more examples of web construction, check out Samuel Zschokke's amazing site.