1. A method comprising: in a network system, receiving items of content captured by electronic devices associated with users, the received items being uploaded to the network system, and the network system is configured to stream or download the received item to other users of the network system; with one or more processors, executing instructions to perform the acts of: extracting digital watermarks in audio signals from the received items of captured content; with watermark IDs decoded from the digital watermark, obtaining metadata about the received items; correlating metadata associated with the received items; and presenting correlated metadata for plural received items.