Universal Viewer is not showing Video

We have had Omeka S running for quite sometime. Latest version of everything installed and everything works as expected. Universal viewer works fine when using images and such but just leaves a blank space where video is supposed to be presented. If anyone has any advice on where to start on this? Its puzzling that it works for images but not video, this is an inherited project so many hands have touched it before and I am new to this.
Thanks in advance!

Normally, videos are working fine, you can see an example on the digital library of Université Paris Sciences Lettres (PSL) here with universal viewer :