1. A method for comparing videos including: detecting local features in frames of a video; determining the positions of detected local features in a first frame compared to their respective positions in a succeeding second frame; for at least some of the detected local features, generating a movement indicator representing the position of a local feature in the first frame relative to the position of said local feature in the second frame, the movement indicator including an orientation, to obtain a plurality of movement indicators; grouping movement indicators by orientation ranges; summing the number of grouped movement indicators in an orientation range to obtain a value for that orientation range; obtaining a time series of values for at least one given orientation range by determining the positions of detected local features in a first frame compared to their respective positions in a succeeding second frame for a plurality of pairs of frames; and for at least one orientation range, comparing a first time series of values for a first video with a second time series of values for a second video to determine the similarity of the first and second videos.