good viewer, almost exactly what I wanted.
some sites load only the thumbnails of the images, so this add ends up showing those instead of the images,what defeats the purpose of this add-on

Works great on reddit and most sites.

But does not work with searx (eg., search.disroot.org) search engine. Could you check?

Very useful. So much better than Firefox "Page Info->media".
It would be great with an extra option: "Choose background color", replacing the semi-transparent view of the webpage.