Hi!
I encountered two problems with external audio track in SMPlayer 0.8.0 and 0.8.1:
1) If the original video file contains 2 audio tracks and then you load an external audio track, SMPlayer still shows 2 audio tracks in its menu. But if you try to select the 2nd track now, SMPlayer just does not play at all.
I think, SMPlayer should either show 3 audio tracks in its menu (i.e. 2 internal + 1 external audio track) and allow to switch between them on-the-fly, or show just 1 audio track when you loaded the external one.
2) If you watched a video file with an external audio track loaded and then exited SMPlayer with "Remember settings for all files" option on, SMPlayer saves the path to external audion track in its file's settings. If you then rename the external audio track and want to play the video file, SMPlayer does not allow to play the file since it can not find the external audio track. I think, SMPlayer must use the internal audio track in this case to allow to play the video anyway.
But anyway, SMPlayer is the best!
Thanks, Vitalii.