There are a really startling number of “treadmill accident” videos on YouTube — some depicting true accidents, others deliberate setups. Why would anyone deliberately attempt to do a headstand on a moving treadmill? I dunno, but dude, that looks painful. That little safety thing you clip to yourself that stops the treadmill if you trip? Not just for decoration, folks!
In workshops I often use this comic when I talk about YouTube:
Anyway, the treadmill accident videos were mostly interesting because they led to some videos of construction workers doing highly inadvisable but clearly fun things with heavy equipment. Worth two minutes of your life, IMO.