The NoPages skin, unlike most jAlbum skins, does not produce any album pages. It does not generate any HTML or CSS files. The skin is more in the nature of a utility program, designed to provide a way to take images and videos and have them processed by the jAlbum image and video engines. It can be used, for example, to create high-quality scaled images from large originals or to produce thumbnails for use in contexts other than a jAlbum-produced photo album.
If video files are added to the album project, jAlbum will process them, converting them to the MP4 format, placing the index at the beginning of the file, which enables streaming of the video (i.e., it can begin playing before the entire file has been downloaded to the visitor's computer), and reducing the overall file size considerably, generally without compromising quality. If videos are included in a regular jAlbum project, there's no need to pre-process them with the NoPages skin - this batch processing might be useful, however, if you intend to use the videos in another context, or if you want to provide them to others, not as part of an album.