Found this video on youtube... Pretty grusome, but informational =
YouTube - Worker pulled through woodchipper
My thoughts/condolences go out to his family.
This is the reason why we don't let newbies run ANY of our gear until we fully induct and train them, then they are supervised for a set amount of time before we let them run the stuff by themselves. Ranging from our smallest saws, to our stumpgrinder to the chipper.