Despite the idiotic title of the article, this is kinda cool! No indication of how many yo-yo hours are necessary to charge the phone, though. I hope you have strong wrists!
How well do yo-yos work when a USB cable is plugged into one side?
its hard to tell your tone, but i believe you yo-yo first, charging the internal batteries, and when you're done, you plug in your iPhone (or other USB device).