We conducted a series of experiments to assess the feasibility of synthesized narrations to describe online videos. To reduce the cultural bias, we included adult blind or low-vision participants from Japan and the U.S. in the main study. Our research also includes a follow-up study we conducted in Japan to assess the effectiveness of synthesized video descriptions in realistic situations. The results showed that synthesized video descriptions were generally accepted in both countries. We also found that appropriate technology support allowed a novice describer to make effective video descriptions. Based on these results, we discuss the implications for developing a technology platform for describing online videos. © 2010 ACM.