It is saved as BANDCAMP_URL in the tags. If you want to save it in the more common tag field WWW, then open up the src file in notepad, or your favorite text editor, and change the line outputto "BANDCAMP_URL" to outputto "WWW"
Anyways, bandcamp changed their pages again, so here's updated src files:
&Bandcamp#&1 Def&ault.src (4.7 KB) &Bandcamp#&2 &URL.src (3.6 KB)