Cannot Download Music from Vk

Hello, There are two ways to install the extension onto Android.
1. Install mobile Mozilla Firefox: https://play.google.com/store/apps/details?id=org.mozilla.firefox
Then install the SaveFrom.net helper extension from our website: http://en.savefrom.net
2. Install mobile browser Yandex Browser: https://play.google.com/store/apps/details?id=com.yandex.browser.alpha
Then the SaveFrom.net Helper extension from the Opera Store:
https://addons.opera.com/addons/extensions/details/savefromnet-helper/?display=en
What's more, there is the application for Android to download videos from YouTube:

http://sf-apps.com/android/SaveFromNet.apk