VLC has an addons/extension site: addons.videolan.org.
- put the file in the vlc subfile /lua/extensions, by default:
* Windows (all users): %ProgramFiles%\VideoLAN\VLC\lua\extensions\
* Windows (current user): %APPDATA%\vlc\lua\extensions\
* Linux (all users): /usr/lib/vlc/lua/extensions/
* Linux (current user): ~/.local/share/vlc/lua/extensions/
* Mac OS X (all users): /Applications/VLC.app/Contents/MacOS/share/lua/extensions/
(create directories if they don't exist)
VLSub: Search and download subtitles from opensubtitles.org using the hash of the video currently playing or its title. Also here.
Subtitle Finder: Get the subtitles of movies from the internet, currently only from OpenSubtitles.org (just displays subs, doesn't saves them; but sometimes finds much more subs).
Modified version to save subtitles here.
This extensions are better used at the same time.