A hierarchical publish/subscribe network is employed to produce and distribute special effects to users to complement displayed video information. A top level broker in the network receives a plurality of data streams corresponding to a respective plurality of primary special. A service provider makes a subscription request for one of said primary special effects and receives the corresponding selected data stream. The selected data stream is transformed into at least one further data stream, corresponding to a further special effect. The further data stream is published to a lower level broker associated with the service provider. In response to a user subscription request for the further special effect, the lower level broker publishes the further data stream to a user interface for presentation to the user in association with the displayed video information.