1. A system for filtering content of multimedia data containers, comprising: a network interface for receiving said multimedia data containers from a network; and a plurality of server units, each server unit comprising a set of processors and a set of memory devices, having installed thereon: a filter-definition module, having computer readable instructions stored in a computer readable storage medium, for acquisition of definitions of a set of filters from a user, each filter specifying a definition of a content descriptor, a descriptor criterion, and an operator; a rule-construction module, having computer readable instructions stored in a computer readable storage medium, for acquisition of a set of content-filtering rules from said user, each rule specifying a Boolean expression of a subset of said filters and a filtering action; a module for characterizing content of each component of a multimedia data container, determining said content descriptor, applying said operator, and determining a state of said each filter; a module for determining a binary output of each said rule; and a module for performing a filtering action relevant to said content subject to a preset value of said binary output.