YouTube Go is an official Google app that has been slimmed out of unnecessary additions. It was released in February this year, however, it was held on the basis of open beta testing. Google has stated that YouTube Go is stable enough. Therefore, the version 0.65.59 is the first release without beta note. The additional advantage of YouTube Go is the ability to download selected videos to watch them offline.
The YouTube Go app has been released primarily for developing countries where mobile Internet is not a widely available service. Wi-Fi hotspots may help, but their availability is also limited. Therefore, the new Google app not only limits the quality of the content you view in order to save data usage, but it also has the offline mode. Currently YouTube Go is officially only available in Algeria, Egypt, Ghana, India, Indonesia, Jordan, Kenya, Libya, Malaysia, Nigeria, Pakistan, Philippines, South Africa, Thailand, Vietnam and Yemen.
YouTube Go is not officially available in many countries, but you can install it.
Although the YouTube Go app is already in beta, unfortunately you will not find it in the Play Store because of regional restrictions. However, you can work around this by downloading the installation file from the APK Mirror page, which uses the Google application database directly. In spite of this, you will not be able to use offline mode, because of copyright reasons. Downloading of recordings is only available for some clips. Most people will find nothing interesting in the new Google app. YouTube Go applications should be useful for people who have older devices. From the same reason they also use lite versions of applications such as Facebook and Messenger.
Source: Google Play