Well, don't know, it should work with that....
Verify, it is registered succesfully, with
GSpot (View->Installed Codecs->Audio).
You could also try the Radium MP3 Codec:
but it's the same...
or try to play that video with
VideoLAN player.
Or can install
FFDShow if nothing else works.
Then don't forget to set its audio mp3 decoding in
Audio filter configuration from Start Menu (set it from 'disabled' to 'mp3lib').