Netflix is commonly referred as an over-the-top (OTT) media, and it takes a role of a video platform changing the market. The purpose of this research is to explain the competition in Korean video platform market, in particular competition between traditional pay TV and OTT. In this study, the theory of the niche is adopted to explain the competitive dynamics in video platform market in Korea. This theory is a unique framework to conceptualize and empirically measure the impact of new media on the old one. It explains and predicts the existence, displacement, and extirpation of players in the ecosystem. To make up for the previous researches, multiple resources such as gratification and time spent using media are measured in this study. The result indicates that the case of the Korean market was significantly different from the case of America, in that competition between traditional pay TV and OTT was not severe.