We had tried in the past (several times!) to make this option available for you but Facebook technical issues (they got them too) made difficult, when not impossible, to make this option available.
We are super happy to announce that, after some hard work and coordination with Facebook team, we are releasing the possibility to create CA directly from the creation form for the videos used for promotion. This will make video retargeting super easy and efficient, will also open the doors for a wide range of marketing possibilities.
How does it look like? See here: