We present the effect of video demonstrations on student performance in an online Astronomy course. We find that students who watched the videos performed better on related exam questions compared to those who did not watch the videos. We also find that students in the online course performed as well as students in a nearly identical face-to-face course on video-related questions but worse on other questions. Finally, we find that online students performed at par with face-to-face students on the Astronomy Diagnostic Test. These videos are freely available on YouTube, Google Videos, and iTunes. (Contains 3 tables and 1 figure.)