Tapping on the youtube icon (on the toolbar) opens up the demo video - if one exists. You’ll notice that tapping on the youtube icon shows two more heroes. One with three dots (meant to edit the video) and the other with an “x” (meant to close all icons)
You can always edit your demo videos through the icon with three dots next to the video. You can only add videos from youtube to this platform. Copy the link from the youtube app or a web link starting with “https://www.youtube.com/….”
To delete a youtube video, just add three spaces “ “ to in the input link.
To hide the demo video, click on the “x” on the right side of the toolbar. Alternatively, you can click on any other tool which will hide the demo in favor of what you selected. A note, all of these actions will only mask the video, not pause it.