Hello Frank,
Seems like Viemo changed the default setting and now the video is only embeddable if this one is selected otherwise it would not show on the website.
Hide from Vimeo
Private on your account, but embeddable anywhere.
You can select this new option and I have checked if you will apply domain restriction it can not be embedded on any other website and nor it can be viewable on Vimeo.
See screenshot.