Salut! This idx/sub file combination is for use on your desktop or laptop computer to watch The Last days of Disco with French subtitles. You could use a nice free player like VLC (since Microsoft cant afford to make a better player) and simplyload the idx file when you open the divx avi file in the file open menu.
The movie I have converted here for you has the subs already embedded for divx players so it will certainly show on your disc player at home, and on your desktop either as-is if your software is compatible, or use VLC with these added files here and you'll have French all the way! Merci, Michael Chessman