Even an untrained schlub like me knows that if an unusual sound shows up while running a machine, there's probably something wrong. Anytime I'm dealing with anthing mechanical, a change in sound or vibration means I at least take load off it and start trying to trace the potential problem. In this case, it may not have saved the machine, but it might have rescued the operator's underwear.
Either way, a lack of injuries is a good thing, though it's still kinda sad to see a good machine go all to pieces like that. I hope it can be saved, and I hope the operator remembers the lesson he learned today.