I believe the website and extension utilizes the music from a bad rip, which was slower than the original game due to an error. The proper rip, accurate to the in game sound, can be found linked. Use foobar2000 to listen and to change from USF to MP3, if needed.
Doubutsu_no_Mori_2001-04-14Nintendo_EADNintendoNintendo_64rr.zip
I believe the website and extension utilizes the music from a bad rip, which was slower than the original game due to an error. The proper rip, accurate to the in game sound, can be found linked. Use foobar2000 to listen and to change from USF to MP3, if needed. Doubutsu_no_Mori_2001-04-14Nintendo_EADNintendoNintendo_64rr.zip