That's my friend Larry's kid powered gravel screening plant and Sauerman Slackline cable excavator. That thing has been around a few years. My kids played with it when they were little. I tried to get him to bring it to Cabin Fever but he couldn't come down. It will be at the HCEA show I advertised this September.
Here's a video of it in action.
http://www.youtube.com/watch?v=0PNqW...4&feature=plcp