You can now download YouTube videos on your Android or iOS device using the official YouTube app itself and watch the videos later while you are offline or on a slow connection.
It takes a few easy steps to download a video on the YouTube app. Open a video, tap the download button (see screenshot), choose the resolution for the downloaded video and it will begin to download on your device. There’s a new “Offline” section in the YouTube app where you can find a list of all videos that are currently in the download queue or available for offline watching.
That said, there are certain obvious limitations. One, not every video available on the YouTube website is available for download. Also, the downloaded videos can only be watched inside the YouTube app. There are however no restrictions around the number of videos that you can take offline with the YouTube app, you are only limited by the free storage available on your iPhone or Android phone.