How do I get the video to fit in the banner of Facebook?
Make your project/composite shot timeline size 820x462in accordance with the guidlines provided by facebook.
There are many guides on google.
Your cover video should have a maximum resolution of 1080p, and you can upload it in .mp4 or .mov. Other formats are possible, but those two are the ones Facebook recommends. You can always use a free online file converter if you have a different file type.
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