According to reports, AndroidYouTube is developing a new Smart Downloads feature that downloads 20 videos per week based on your viewing habits. Of course, the app will only use Wi-Fi to download the content. The goal is to save mobile data while watching your favorite channels while on the go.
Google is experimenting with Smart Downloads in its YouTube app for Android. Only Premium customers in Europe get access to the new functionality. It may be turned on by going to Settings > Try new features > Try it out. To participate in the testing stage, you must do so before February 14th.
If you run out of storage, the app will inform you before downloading any videos, and you may view the downloaded videos in your Library tab among the rest of your downloaded videos.