If you aren't able to add a call to action to a video ad, check your ad for the following:

• If you didn't choose a Call to Action button when creating your ad, or chose No Button, your ad will appear without a Call to Action.
• If your marketing objective is Engagement, you can't add a call-to-action button to an existing post or event if it doesn't have a call-to-action button. To add a call-to-action button, you should create a new video ad instead.
• When you add a Canvas to a video ad, you can't add a call-to-action button to the ad. Because Canvas is a mobile-optimised experience that opens when people see the ad in their feeds, a call-to-action button isn't available.
• If your marketing objective is Brand Awareness, Reach or Video Views, select Add a website URL to see the Call to action drop-down menu.

Learn more about adding a call-to-action button to a video ad.

* Nguồn: Facebook