I think if a file is listed as public and you were to give out your unique url for it, it's not instantly downloadable by others. Rather they'd just see the preview picture and description with an option to buy, and if they do all payment goes to B2B as usual. I believe the original owner can set a commission rate so that people reselling a clip would get a cut.
For example - Dave sets the rate to 10%. I buy clip A, set it to public and distribute my unique url for it. Sales from this link would be 90% to B2B and 10% to me.
At the moment its set to 0% so all sales from these links go 100% to B2B, so no harm done.
That's how I understand it anyway - I could be
totally wrong.