Simply follow the 3 steps in the link below to generate a HTML snippet so you can copy and paste it into your new widget:
[ https://developers.facebook.com/docs/plugins/embedded-video-player#add-code-manually ]
The code is pretty much like this:
https://www.facebook.com/FacebookDevelopers/videos/10152454700553553/" data-width="500">
Facebook's tutorial recommends using javascript version 2.5 but it works when you edit the code to set version = 2.8 as you can see in the example above.
Warning:
Our team is not able to assist you on installing and maintaining third-party application codes in any way.
Adding scripts, snippets and other pieces of code in Custom Content Widgets may crash your site. We recommend to create a custom page to test widgets before changing the live version of your pages.