When video captures are extracted by the cinemetrics extractor, the captures can have a large file size for hi-res video. When many of them are stored as section previews, trying to add all of them to Galleria and/or the sections list of a file simultaneously while loading the file webpage takes a lot of time. For this and other similar cases, it would be good if sections could support thumbnails as well as previews, thumbnails being lower-res copies of the previews of the section. Same may apply for e.g. large sections of gigaimages.