YouTube Go youtube app
YouTube Go is an official app to download videos on your Android. You can download any video and watch it offline without internet connection. This is pretty useful if you don't have unlimited access to mobile data. It is simple but effective tool to control your data usage and avoid unwanted bills.
The best YouTube Go feature is the option to download videos to your phone. Along it has options for preview before stream or download. Then you select the desired resolution (HD or basic) and download it to phone or SD card.
Send any downloaded video with YouTube Go's Bluetooth connectivity. You'll be able to stream to any Bluetooth enabled device in range. Thanks to this you can share videos without wasting your data.
It does not offer full functionality of official YouTube app, but it is great for people with poor network access. If you have unstable or slow connection, use it and save videos to your phone.