This is an excellent idea
As a musician I love the possibilities that this would enable for sorting out a fair way to use samples in producing new works. I’m thinking that in a similar way to the ownership split, the ability to make micro payments means that original works would have a “sample cost” as part of the MXVD where one would pay for the fraction of the original sampled. If this was charged as a percentage of the sales garnered by the derivative work, it would also mean mashup makers wouldn’t pay unless they sold their mashups.
As to money from mixes, I reckon that most musicians see mixes as promos that get their stuff heard by a wider audience and would not want payment AS LONG AS MIXES HAVE PROPER TRACKLISTS and the mixes are offered free of charge. If the .bc codec was also used for mixes, this could also embed tracklists into a mix, which would be great.
Look at the difference between Soundcloud’s new policy of taking down mixes where tracks used haven’t been explicitly authorised vs something like mixcloud which encourages mix makers to create tracklists and then automatically makes the tracks in the list link to digital stores where they can be bought. The latter seems far better to me.