BFSTM file
From Pikmin Technical KB
.bfstm
files are the streamed music in Pikmin 3. Some of these songs contain several tracks, which are enabled or disabled in-game to make the music dynamic. This game's BFSTM files can be found in /CMCmn/audio/audiores/stream
. A rundown of the format can be found here
. A list of what files match what songs can be found here.