A method for decoding auxiliary data from media signals in multimedia content decodes watermarks from different media signals and uses the watermarks to control processing of the multimedia content. A copy control method decodes a watermark from one of the media signals in multimedia content, and uses the watermark to control processing of the multimedia content. Another method uses a watermark decoded from a first media signal to decode a second media signal. Yet another method uses a watermark decoded from a media signal to decode metadata associated with the media signal. Finally, another method forms a key for decoding data from at least first and second watermarks extracted from first and second media signals.