Our clients know that we keep reminding them about having multiple formats once we produced the video. The reason is simple, Facebook wants native content and the audience are favourable that the video played in certain aspect ratio. Thus, the same video you may want to have at least 3 different format/ratio; for website/youtube, facebook and a teaser for (promotions). It's a strategy! Remember that your audience is conditioned differently on a different platform, and to have the maximum outreach, format your video at their convenience. Let me know if you need help on how to format your videos into those different platforms.