BS.Player's Online Subtitles service is powered by:
www.OpenSubtitles.org
www.subtitles.com.br
To enable it (it should be on by default) go to
Preferences>
Subtitles>tab
Online subtitles> check
Enable online subtitles.
Subs will be saved to the folder defined in
Save downloaded subtitles to field. Options are 1. in folder where the movie is located, or 2. in SUBS sub-folder.