The way I have interpreted it is..... And I am more than happy to be wrong.
CPL/ATPL can pretty much do what they like within there ratings and be payed or not payed but they don't have to shell out any money for what ever they do.
PPL- They can't get free hours or any form benefit from the flight unless they chip in to the direct running costs or they are part of the excemptions.
Personally I disagree with the current state of affairs. There should be someway that a PPL can ferry a mates aircraft from A to B as a favour without a CPL. It shouldn't be the case though that a PPL can ferry an aircraft to help out a commercial company eg flying school, or say position in a photo ops aircraft for a job.