When you drag a video element and drop it on your page, a property page will ask for some details. Most important, it wants to know which video you want to play.
You need to enter a link to youtube.com. The link is created when you use the share function on youtube.com.
You can specify the size of the video screen and the proportions used. (16 to 9 or 4 to 3). The size can be updated too. You need to use it several times and see for yourself.
Upload audio and embed it into a page with this element.