Those Sons of Mary should not be messing around with Sons-of-Martha stuff.
Looks like they were fine with their butts on the rail and their rubber soled shoes on the ground. But then one of them grounded out through his back. That will leave a mark.
Having lost a friend’s son who was a high tension line lineman up in a bucket and his arm with a cotton shirt sleeve and large gloves— brushed high voltage, and was killed horribly— by grounding to something in the bucket... you are correct. 2 more seconds and more than a mark.