Seems like the YouTube Video widget doesn't work - dragging it to the page doesn't do anything. And I can add "social media" buttons but it's not clear how one edits what they link to or which ones show up.
It works fine for me. You need to drag it on the green lines. The problem is now getting rid of that video :/ can't drag it to trash.
Aha. That's a really narrow hit target. Yeah, it seems like if you place a video and decide you don't want it there after all or want it somewhere else, all you can do is delete the whole tab containing the video and start over. A work in progress, I suppose. :-)