1. An information processor comprising: a frame extraction unit which extracts frame data from a moving image file in accordance with a plurality of predetermined rules; a decoding unit which decodes frame data extracted by the frame extraction unit; and a display unit which simultaneously displays a plurality of thumbnail arrays which each correspond to one of the rules, in each of the thumbnail arrays being aligned, in the order of appearance in the moving image, the images of frames decoded by the decoding unit with respect to each of the rules.