there’s a bit of a work around but had a client who wanted it so needed to do it.
convert image to MP4 in Photoshop (or other editing tool you use), I went with 30 seconds , if not sure how to then links to youtube vid below is good.
followed by the next one on how to post
you will need this app which installs some metadata in the vid before you upload, not sure exactly what it does but it works and I was in a hurry.
Hope that helps