I'm not used to using the single position crimp tools, so I made a rookie mistake. I was using the correct size jaw to crimp the wire section, but then incorrectly using the next size up to crimp the insulation. In reality I should have been using the same size jaw for both.
After I'd made the video I applied several of each crimp with the basic iWiss tool using the same (1.6mm) jaw and it did a perfect job of them all.

It appears that the Dupont style connector termination tools actually curve the insulation grip around it, but don't bite into it. There's a very thorough guide to crimps and tools here:
http://tech.mattmillman.com/info/crim...

A search on eBay shows that Iwiss seem to do mainly crimping tools. If you search for the keyword Iwiss and lowest price first you'll find the IWS2820 (2820AWG) in the results.
https://www.ebay.com/sch/i.html?_from...

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