Only used it a few times before the pony hurt his tendon but while I wouldn't have stood all my weight on one stirrup as the video showed it did do the job!
Pony now retired so it's not really had a full test.
You would have to work really hard to over tighten it - the outer elastic band never goes tight - it's like a balance band and because the inner band is also elastic it has a lot of give.Hope that makes sense!
The only thing I watched out for was that it didn't catch any hairs and pull them but then mine was on an unclipped hairy haffie