As people increasingly access movies, user-created content, and linear television programs through the Internet, scholars are paying attention to the effect of online video services on various media markets, including the broadcasting market. Focusing on South Korea, this study examines how changes in the time spent on online video services affect the time spent on other media: terrestrial TV, pay TV, terrestrial DMB, radio, SNSs, games, newspapers, and books. This study also examines how this time displacement effect of online videos on other media differs across various video content categories. The results show that an increase in the time spent on online video services reduces the time spent on cable TV and games. Among the online video content categories, broadcast network programs and cable network programs reduced the time spent on cable TV, and movies reduced the time spent on games. Moreover, the amount of time spent viewing online videos reduced the time spent on non-media activities but increased sleeping time.