Have you tried the option in BSplayer Audio settings (CTRL+P -> Audio -> Default audio stream)?
Or the playlist option "§Audio stream" (you need to use "old style playlist" under Playlist settings, then in the opened playlist select the loaded movie and in the right panel select the 2nd audio stream)?
Otherwise, try to write the commandline like this
Code:
"path\bsplayer.exe" -as2 movie.avi
instead of
Code:
"path\bsplayer.exe" movie.avi -as2
It's also available an audio plugin (made by
RafkeP) that enables the 2nd audio stream by default, just search the forum.
P.S.
Can you also tell us the file type? AVI, OGM, MKV? Codec used to encode it?