There are plenty of applications for downloading YouTube videos to watch without needing an internet connection, to share them with others on WhatsApp or other chat and messaging apps, or to use them for you own purposes. One of them is arkTube.
As easy as sharing on the YouTube app
This application doesn't work as a YouTube client, like other apps. What users have to do here is to go to the official video app, press share, and select arkTube. Once done, you will be able to download content, albeit with varying resolution.
Now, the fun part here is that in order to use all of the app's functions, you will have to make a small donation to its developers. So, you can go for this option, which is actually pretty convenient due to the actual functioning of the app and it being totally ad-free, or go for other options, like TubeMate or any of the others that you will find here on Malavida and which are totally free.