Here's a Google-translated changelog for this latest release:
MP3PlayerPlugin UPDATE v1.4:
plug-in music playback
Plug in the operation of the light, skip, add the blending mode menu
How can such changes in the expression of the specified channel mute
And here's a translation of the control scheme:
L + R + Left / Right = select other songs
L + R + [] = Pause
L + R + O = Change the order of play (in order, randomly, etc.)
L + R + Triangle = Play the song again.
L + R + Up / Down = change in volume.