Run subnew.py with python3 in the directory with your movie files and it will download the english subtitles. Look at the code for further information. It is much clearer in ver 2. The code is split into seperate files and now easier to handle. Feel free to pull and improve!!
alias sub='python3 /path/to/subnew.py'
I have actually written a completely new subtitle downloader in perl. I plan to reimplement it in python, it has opensubtitles support.