1. An automated system for the capture, management and playback of a presentation given by a live speaker having audio and visual information components, comprising: a live presentation capture system, including: audio input means for sensing an audio portion of a live presentation and for producing audio signal information corresponding to said audio portion; video input means for sensing a visual portion of said live presentation and for producing video signal information corresponding to said visual portion; user input means for permitting a user to manually input presentation identification information relating to said live presentation; and processing means connected to the audio, video and user input means for converting said audio signal information, video signal information and presentation identification information to machine-readable format in the form of, respectively, an audio data stream, a video data stream and presentation identification data, said processing means including storage means for receiving said audio signal information and said video signal information upon conversion to machine-readable format and for assembling said audio data stream and said video data stream, respectively, by storage in a sequence of storage locations whose addresses correspond to elapsed times from a presentation start point included in said presentation identification data, said processing means further including video processing means for identifying selected portions of said video data stream to be stored in said storage means, said video data stream corresponding to a series of static video presentation images and said video processing means including means for preventing storage of said video data stream corresponding to transitions between said static video presentation images; a presentation management system coupled to said presentation capture system, including: a presentation database; means for receiving said audio and video data streams and said presentation identification data; means for combining the received audio and video data streams into a single presentation object and indexing that presentation object by said presentation identification data; means for storing said presentation object with other presentation objects in said presentation database; and means for retrieving said presentation object from said presentation database in response to a search request including index data contained in said presentation identification data; a presentation playback system coupled to said presentation management system, including: query means connected to said presentation management system for providing a search request including index data; output interface means for displaying search results including presentation management system responses to said search request; replay request means for selecting a presentation object from said search results; audio output means for outputting audio information from a selected presentation object; and video output means for outputting video information in response to said selected presentation object.