Sometimes when embedding a video, you may run into the error: "Sorry, we cannot use this video for embedding"
In this situation there are several things to check:
When embedding a video from YouTube and Vimeo, ensure that you are embedding the video itself and not a channel or a playlist.
The URL you paste in should be in the format: https://www.youtube.com/watch?v=frdj1zb9sMY
On both YouTube and Vimeo you can set the video to not be embeddable. Check the settings to ensure that the video is publicly viewable and can be embedded.
If the above all looks correct, then wait some hours and try again. Unfortunately, we have run into the problem where a recently published video is unable to be embedded because YouTube's API returns an error - in this case, the fault is with YouTube and we just have to wait for their API to return the correct information. :(