I guess this plugin may have been superceded by the new [audio] shortcode in 3.6 but because I was having problems with that I decided on trying this plugin.
The plugin works with all common browsers except IE where it gives the message "Error: Unsupported audio type or invalid file path"
Yet strangely enough it works if I put IE into IE8 mode. Given that file path must be valid I guess there is some configuration which I am missing.
See http://dev.britishpolio.org.uk/polio-a-living-history/oral-history/interviews-11-20/ - note this may change as I try and work it out!!