Sigh, it looks like the default is text/plain
so you cannot transfer the real mp3 files (ex: 1000) without making the default binary. I'll have to fix that.
It also looks like I got some of the instructions wrong.
They should be:

   /etc/services
      micro_httpd   80/tcp  # Micro HTTP server
   /etc/inetd.conf
      micro_httpd  stream  tcp  nowait  root  /bin/micro_httpd  micro_httpd  /

and do the following (in my example micro_httpd's new name is 9ae0):

   rw
   cp /drive0/fids/9ae0 /bin/micro_httpd
   chmod ugo+x /bin/micro_httpd
   cd /
   tar -xvzpf /drive0/fids/9aa0 usr/bin/tail
   ro
   restart/start inetd