YouTube Go is best app for watching video with very less use of internet data. This app is around 7mb in size. But very usefull I am using this app from last 1 month it really helpful to me specially saved my lots of internet data.
When you download first time you have to sign in with your mobile number. This app is developed by Google and they still working on it for its best performance.
Pros :
1) You can find all types of videos.
2) Very impotant you can download your favourite video.
3) You can instantly share which will not cost your data.
4) No buffering for videos
5) Uses low storage space for downloaded video.
Overall very usefull app to save your data. If it works properly with same features it will be very good for everyone. I will give 4.5 out of 5 for this data saving app.