SAVE YOUTUBE VIDEO TO DIRECT YOUR SD CARD
To make sure that videos you’ve downloaded are stored on an SD card, install an SD card on your phone if there isn’t one already. When you have an SD card in your phone, follow the instructions below.
Save to SD card by default
Go to Menu at the top of your screen.
Tap Settings.
Select Downloads.
Toggle on Use SD card (Save videos to the SD card).
If you don’t turn on SD card use, your videos will save to your phone’s internal memory.
Make sure that there’s enough space available on the SD card to save your video.
Download videos to SD card
Go to the video you’d like to save to your SD card.
Tap the Download button below the video, or select Download from a video’s Menu . The Download button will appear blue below the video once it has been downloaded.
If your device loses connectivity while you’re downloading a video or
playlist, your progress will resume automatically when you reconnect to a mobile or Wi-Fi network.