I'm not seeing any dead links there? That page has always been a listing of the mp3 files on the physical CD that comes with his book, only some of which were ever put online.

BTW, Sethares' research https://en.wikipedia.org/wiki/William_Sethares goes way beyond tuning music to simple ratios. His whole book is about working with a model of sounds being "in tune" with one another that doesn't just boil down to that.