12. The apparatus according to claim 9 , wherein the processor is configured to receive from a human moderator an instruction to synchronize a selected media item with a component of the textual input, and to automatically construct the video clip by synchronizing the selected media item with a narration of the component in the audio narration.
9. Apparatus for multimedia content generation, comprising: an interface for communicating over a communication network; and a processor, which is configured to receive a textual input, to estimate, before receiving an audio narration of the textual input, occurrence times of respective components of the audio narration, to automatically retrieve, from one or more media databases over the communication network, a plurality of media items that are relevant to the textual input, to receive user input, which selects one or more of the automatically-retrieved media items and correlates one or more of the selected media items in time with the textual input, to receive an audio narration of the textual input, and to automatically construct a video clip, which comprises the audio narration and the selected media items scheduled in accordance with the user input, by scheduling the selected media items in accordance with the estimated occurrence times.