Look at the documention of `\with-url` in the PDF version of the NR: The link in the included snippet (to 'lilypond.org') doesn't work. This is a limitation of pdfTeX (or XeTeX), which drops all links and annotations for included PDF files.
Masamichi-san, is it possible to extend `extractpdfmark` to cover this, too? Looking around it seems that the tool 'pax' ('PDFAnnotExtractor') in TeXLive can do that. However, it is based on Java... https://github.com/bastien-roucaries/latex-pax The reason why I ask is the planned inclusion of the Visual Grob Index in the NR – all grobs shown have links to the corresponding documentation. If these links are lost the value of the index is reduced enormously, and it would be probably better to not include it at all but to have a stand-alone, simple, two-page document instead. Werner