How to watch YouTube videos without internet

Note: It is better to turn on "Add over Wi-Fi only" in the setting so that you only will save the video when you are accessing wifi broadband, not using your mobile data.
以上的视频是教如何离线观看youtube, 在还没有下载前记得将设定改成"Add over Wi-Fi only" 这样只有在有wifi时才会下载，不会用到网线流量。