Action Details
Requirements and how-to articles for Facebook's action:

Requirements
You need this to get it done:

Video Specs
Ratio: 1.91:1 to 9:16
File format: .mp4/.mov recommended, but most video file formats supported.
Maximum file size: 4GB
Maximum video length: 15 seconds
Captions: Not available
Sound: Recommended
Objectives supported: All except Catalogue Sales, Store Visits, Messages
Headline
Write a short headline that grabs people's attention and tells them what the ad is about (maximum of 25 characters.)
Text
A short description to accompany your video (maximum of 90 characters.)
Call-to-action
Choose which type of call-to-action you want people to do when they see your ad.
Duration and Budget
Choose how long you want your ad to run and what your daily budget is.
Payment
Choose currency, enter payment details and pay.
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

0
Facebook Ads Guide - Video (Facebook stories)
Specifications and requirements.
Official
Link missing here or found errors? Improve How-Tos