This article discusses a study which was designed to explore how online scaffolding can be incorporated to support knowledge acquisition in asynchronous discussion. A group of Singapore preservice teachers engaged in collaborative critiquing of videos before they embarked on their video projects to illustrate what constitutes good and bad video production. Separate topic forums and critiquing steps were designed within an asynchronous discussion platform, "Knowledge Community" to provide conceptual and procedural scaffolding to learners on what and how content topics are to be discussed. The online discussion log was content-analyzed together with data from an online survey, reflection log, and interviews. This study contributes to the asynchronous discussion and teacher education literature by demonstrating that carefully designed scaffolding can give rise to on-task discussion that has breadth and depth. Participant perceptions revealed that their knowledge of video production improved substantially after the discussion. Implications to teacher education were then drawn from the findings. (Contains 4 figures.)