YouTube Go is an app by YouTube which consists of many features such as smart offline feature that allows you to save the video to offline mode and even share that video using wifi hotspot connection.
It will also be very beneficial for 2g and typical 3g users. They can watch and download (save offline) videos on low internet connection.And this app will even inform you about the size of the video that you are going to watch or download.
This app has been launched in many countries (even in India), aiming to connect more and more people thought the world and made it easy for those who worry about the internet connection.(slow internet, money used for internet)