The goal behind periscope is that it will only return only correct subtitles so that you can simply relax and enjoy your video without having to double-check that the subtitles match your video before watching it.
This is done by using as much info as available from your file and on the websites. Some websites allow you to use hash of the files, the size/length of the video or the exact file name.
How to use Periscope in Ubuntu
sudo apt-get install python-nautilus python-notify
Then download the 2 .deb packages, install them (just double click) and restart Nautilus:killall nautilus && nautilus
Now, let's set the language you want for the subtitles. Open a terminal and run this command:gedit ~/.config/periscope/config
And simply edit the language in that file.This pretty much takes care of everything you need to do for running Periscope. Now right click a video and select "Find subtitles for this video":

