9. A display device, comprising: a media data processing module configured to process media data; a media data output unit configured to output the processed media data; a buffer configured to buffer the processed media data; an audio input unit configured to receive a speech search command for additional data about the outputted media data from a user; and a processor configured to determine whether the speech search command includes a query term that is immediately searchable by the display device, if the speech search command does include the query term that is immediately searchable by the display device, perform a search for the additional data using the query term that is immediately searchable, if the speech search command does not include the query term that is immediately searchable by the display device, match a portion of the speech command with a query term extracted from audio data of a predetermined amount of the media data that is buffered by the display device prior to a time that the speech search command was received, and perform the search for the additional data using the extracted query term.
9. A display device, comprising: a media data processing module configured to process media data; a media data output unit configured to output the processed media data; a buffer configured to buffer the processed media data; an audio input unit configured to receive a speech search command for additional data about the outputted media data from a user; and a processor configured to determine whether the speech search command includes a query term that is immediately searchable by the display device, if the speech search command does include the query term that is immediately searchable by the display device, perform a search for the additional data using the query term that is immediately searchable, if the speech search command does not include the query term that is immediately searchable by the display device, match a portion of the speech command with a query term extracted from audio data of a predetermined amount of the media data that is buffered by the display device prior to a time that the speech search command was received, and perform the search for the additional data using the extracted query term. 10. The display device of claim 9 , wherein the processor is configured to extract at least one query word from the portion of the speech search command, and determine whether the at least one query word matches the query term that is immediately searchable.