We focus our interest on the engineering of multimedia applications whose purpose is to exploit and make best use of the audiovisual heritage by means of prospective exploration of virtual access to audiovisual documents through multi-structured descriptions of these. Multi-structured descriptions are composed of multiple descriptors that are expressed using the FDL (Feria Description Language) object language whose expressive power is emphasized. FDL notably provides a multimedia developer with operations on descriptions and their inner descriptors, as well as temporal aggregation data types. An experimental multimedia application that makes extensive use of FDL concepts and mechanisms is outlined. It explores the use of syncing between the narrative structure of the text of a play and the narrative structure of different broadcasted performances of this play, at multiple granularity levels.