7. 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 a character string length of the comment which contains each of the words, and number of words included in the comment which contains each of the words.
9. The apparatus according to claim 7 , 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 is upwardly convex.