Adding Call-to-Action buttons on Videos is no longer possible
Mar 18th, 2017 Announcement
As of March 17th, Facebook seems to have disabled the ability to add a Call-to-Action link on Page Videos, which is why we have removed this Superpower.
This change seems by design and probably final since it also affects Videos with CTA created using Facebook's own Power Editor tool. Most likely this change occurred because users were abusing this functionality and were creating an unfriendly environment for other users.
Keep in mind that you can still add a link to your Video Ads. We will let you know if there's any update in the upcoming days.