A method of embedding information in digital content representing media streams. The method includes (1) selecting a set of locations within that digital content reprensenting the media stream to embed information, (2) selecting a set of possible alterations to make at those locations, and (3) making a subset of the possible alterations. The set of locations and possible alterations is herein sometimes called a "watermark." The subset of actual alterations that are made is herein sometimes called a "fingerprint." The method determines a set of locations at which there are alternative versions of digital content representing the same media stream, such as one being the original and one being an alternative version of the same digital content, herein sometimes called the "original movie" and the "alt-movie," or herein sometimes called the "original block" and the "alt-block" for a particular block in the digital content representing the media stream.