Perhaps you sorted this out long ago but this is just a preview of the brushes, hence the jpg file. If you check out z's gallery you'll find the brush source in the v5 brush set [link] instead of here as part of the preview image.
This is so cool! So much so that I foresee that there might be some difficulties in using the brushes without overwhelming the main artwork because the brushes are pretty awesome by itself... So the artwork has to be pretty stunning to match up with the quality. Anyway, what did you use to create this?