The presently claimed invention relates to deriving or extracting information from audio, images and video. One claim recites a method of operating a network filter. The network includes a plurality of network nodes, the network filter is for filtering video or audio. The method includes: monitoring video or audio traffic to a particular network node; identifying a first video or audio at the particular network node through deriving identifying data from data representing the first video or audio, the deriving utilizes at least one programmed multi-purpose computer processor; determining additional information associated with the first video or audio based at least in part on the identifying information; and notifying the network node of the presence of the additional information.