4. The apparatus according to claim 1 , wherein the second acquisition unit is configured to acquire the estimated value of each of the words, based on an article of each of the words and a frequency of detection of each of the words.
4. The apparatus according to claim 1 , wherein the second acquisition unit is configured to acquire the estimated value of each of the words, based on an article of each of the words and a frequency of detection of each of the words. 5. The apparatus according to claim 4 , wherein the extraction unit is configured to extract, from the estimated value distributions, a start time and an end time of a zone of the video content corresponding to one of the estimated value distributions which exceeds a threshold value.