v2. Ringtones - file type not supported

In my Browser (Firefox v20), when I select Ringtones, ensure Phone tab is selected, then hover the cursor over a ringtone a click the Play icon, I get the message: File type not supported, and no ringtone is played on either the phone, or through the PC speaker.

I am running Android 2.1 - update 1 on a Samsung GT-i5700 with over 3Gb of free space.