Aside from the wear and sloppiness from 3D printed parts, I still have to say that this is pretty cool. Very ingenious. It must have taken him a long time to match the "vector" movements and translate them to the lobes on the discs. He explains the math he uses to determine the output. This would make a good science project for those with kids.
Oh to have had something like this 30 years ago when galvos were so far out of my price range and anything beyond 15mW was a wallet pipe-dream. This would have been cool. Crude but then, the best I could manage at the time was a 4" woofer, a spring, a mirror and some hot glue!