For Google Chrome version 35 and later on OS Windows:
Install OrangeMonkey extension.
Open helper.user.js link and accept the installation.
If you have difficulties installing OrangeMonkey extension, we have a solution for you:
Install Chameleon extension and SaveFrom helper from the Opera store.
In other cases
Go to the extension page, click the download button and accept the downloading.
Click on the icon on the browser toolbar and select "Tools" - "Extensions".
Drag and drop the extension file "helper_last.crx" from the folder you've download it to the extension page and simply press "Add" button in the appeared popup.