To embed a youtube or vimeo video on an editable page of the site, please follow the instructions below:
1) Go to the site page and click Enable Editing
2) Click on the editable area where you want to embed the video
3) Click Source option on the WYSIWYG editor.
4) Add this html code in the editor : <iframe src="video_link_here" width="500" height="400"></iframe>
Change the video_link_here part with the video URL. The URL would look like this : https://www.youtube.com/watch?v=2UZkQeq8Eww
You can get the URL from the share button on youtube or vimeo. In the above code, you can also adjust the width and height of the frame according to your page and content.
5) Once added, click OK and Save Changes.
6) Refresh your page to see the changes.
Please note: The video you embed should be publicly available.