The rising trend of MOOCs has attracted wide ranging research interests. Among all the existing studies related to MOOCs, most of them focus on individuals' study behaviors and evaluations (e.g., analysis on click streams for video-watching behavior exploration, etc.) for course design purposes. However, in addition to traditional course materials, MOOCs also provide interactive user forums to encourage students to seek help from peers, which endows the courses with social network formation and interaction. Thus, we present NetworkSeer to help evaluate why MOOC students use forums, and what they do. NetworkSeer visualizes interactions in the forum, including where, when the interactions happen, and why. It also enables filtering out un-targeted groups. A case study is conducted to demonstrate its usefulness.