DiskCatalogMaker will use Quick Look to generate thumbnail images.
DiskCatalogMaker can’t generate a thumbnail image from a file if Finder can’t show its Quick Look preview. (Finder also uses Quick Look to generate a thumbnail image.)
FYI: Some legacy .mov formats are no longer supported by QuickLook of Mac OS X 10.9 or later. (Apple Communities: Quicklook no longer previewing Quicktime videos encoded in ProRes or Animation codec.)