You can easily add YouTube videos to the manage assets to show them through the video pane.
- Go to the back end of your website and click Content > manage assets. On the top left, click Add File.
- In the following window you specify what type of file you add to the media library
- Select "Video"
- Then select "Video hosted on Youtube"
- Copy the URL or unique ID of the video. The unique ID will be found in the video URL
- Then you can select the video when placing a video pane