Recently, the Web technology enables people to watch VoD services such as NicoNico Douga. However, there are so many video contents in the site that "interesting but lower-rated" contents are sunk in them. To support users to find interesting video sunk in NicoNico Douga, a recommendation system of "interesting but lower-rated" contents is proposed. Tags of contents rated as "would be higher rated" are analyzed, and found typical tags attached to such contents. The typical tags may be useful to develop the recommendation system for users in NicoNico Douga.
