In reply to guiltyvictim:
Post a link to the photo?
> 1 - The waist belt was not snug against the participant so they could come off the harness
As far as the harness is cinched 'shorter' than the hips it's safe. When pulling by the back the stomach goes in and there's always slack showing. That does't mean you can come off the harness
> 2 - The carabiner was clipped through the waist belt on the back - so it could freely move sideways, leading to participant potentially spinning around (which apparently did happen to a few people)
No problem with that. Not sure what company you are referring to, but the one i know running this sort of shows have a grounds person keeping control pf the rope in case the abseiler loses control which is the only issue i can see with people 'spinning around'.
> 3 - I don't know if the waist belt of a typical harness can support shocks properly - as a proper snug fit would typically spread the force evenly around
Plenty strong and way more than necessary, but as a bit of trivia, a snug harness will be put through more stress than a loose worn one. (But when when talking about the loads that may make it fail, you'll break before the harness does)
Post edited at 00:58