Step 1.  You must be in Edit Mode. Click the + sign to add a new card.

Step 2. Choose the YouTube Card.

Step 3. In the box highlighted below add the full URL www.youtube.com/
followed by the username, channel ID or video ID

Step 4. In this example, Marley wants to add the Animal Planet to his YouTube card.  www.youtube.com/animalplanet
(Please follow the instructions in the yellow box to add a username, channel id or video id). Click DONE.  
In the second box, you have the option to add a YouTube public playlist. Follow the instructions in the yellow box.

Step 5. Here is the YouTube Card in Edit Mode.  If you wish to see the follower view, click on the Tap Bio avatar and select Follower View.

Step 6. Marley's completed YouTube Card is ready for the world to see!

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