Your media file URLs are given as using Feedproxy but this is in fact a 301 redirect to http://www.redpointchurch.com
Running a test on this in Terminal:
curl -I -r 200-300 http://www.redpointchurch.com/static/audio/audio/Parables/2012-09-02_AM_Jamie_Te rnent_-_The_parable_of_the_Rich_man_and_Lazarus.mp3
Produces the result
HTTP/1.1 200 OK
Date: Fri, 07 Sep 2012 09:07:34 GMT
Server: Apache/2.2.20 (Ubuntu)
Last-Modified: Sun, 02 Sep 2012 21:02:48 GMT
Content-Length: 32624281
Content-Type: audio/mpeg
This would seem to suggest that your server indeed does not support byte-range requests. A successful result would look like this:
HTTP/1.1 206 Partial Content
Date: Mon, 03 Sep 2012 21:59:27 GMT
Server: Apache
Last-Modified: Thu, 23 Aug 2012 04:06:04 GMT
ETag: "3fb8374-2bf169c-4c7e6fa626300"
Accept-Ranges: bytes
Content-Length: 101
Content-Range: bytes 200-300/46077596
Content-Type: audio/mpeg
I can't advise on server technology: the nearest forum to your problem would be for Mac OSX server and I don't know whether anyone there can advice, otherwise you will need to find a forum dedicated to Apache.