In this study, we examined the impact of an English-speaking program on speaking anxiety, and whether the impact differs if the exercises are unscripted and improvised. We used video conversation-based English learning materials, and requested the cooperation of thirty four Japanese high school students who were divided in two groups: an improvisation group that did not prepare a script and a preparation group that prepared a script. We compared and verified the effects before and after implementing the instructions, and examined the impact of different methods on speaking anxiety. Data were collected using an eight-item questionnaire before and after each session; twenty video conversation sessions were conducted. We also changed the methods between the two groups, and seventeen more video conversation sessions were conducted to compare the effects. The results indicated that anxiety about speaking in English was high before conducting the video conversations. Additionally, it was observed that repeated practice using video conversations was statistically significant in reducing speaking anxiety. However, we observed no difference in anxiety reduction between the improvisation group and the preparation group, and found that the experience of practicing speaking in English through video conversations could be useful for reducing speaking anxiety in both groups.