The second clip guy eventually got past only to ditch it (may have no footbrake) but I did not notice anyone warning people until it was too late just lots of people standing to the side watching the carnage grow. My only experience of this type of pile up was the second straight at MX when I saw 2 wheels side on at chest height blocking my path(bike was upside-down) and trying to get up quickly in the dust my footing felt funny and as the dust cleared I was standing on top of someones back trying to not fall completely over, fortunately noone got worse than a bruise but not a nice feeling