The present invention provides methods and apparatus that are helpful for identifying or protecting video. One claim recites a method including: receiving data representing picture elements of video; transforming the data into a frequency domain; comparing characteristics associated with the transformed data to predetermined characteristics that are associated with a first video type, and if the characteristics coincide, determining that the video is of the first video type; and if the characteristics do not coincide, comparing the characteristics of the transformed data to predetermined characteristics that are associated with a second video type, and if the characteristics coincide, determining that the video is of the second video type. Another claim recites a method including: obtaining information associated with a video; selecting a set of information from the obtained information; deriving identifying information from the selected set of information; and providing a security feature in or over data representing picture elements of the video according to the identifying information. Of course, other implementations are provided as well.