From https://bugs.launchpad.net/catfish-search/+bug/1758628 catfish 1.4.4 latest system archlinux thumbnailer installed -ffmpegthumbnailer 2.2.0-1 -tumbler 0.2.0-1 -totem 3.26.0 -raw-thumbnailer 0.2.1-3 tested in gnome search tool and nautilus both can return search with video thumbnail
This was fixed with the upgraded thumbnailer at: https://git.xfce.org/apps/catfish/commit/?id=0dd05be969d0f1d8c6bc60ffbf34b9c39aad7b13 Catfish won't attempt to create thumbnails for videos, but it will display any that already exist.