Creative professionals are creating Virtual Reality (VR) experiences today by capturing spherical videos, but video editing is still done primarily in traditional 2D desktop GUI applications such as Premiere. These interfaces provide limited capabilities for previewing content in a VR headset or for directly manipulating the spherical video in an intuitive way. As a result, editors must alternate between editing on the desktop and previewing in the headset, which is tedious and interrupts the creative process. We demonstrate an application that enables a user to directly edit spherical video while fully immersed in a VR headset. We first interviewed professional VR filmmakers to understand current practice and derived a suitable workflow for in-headset VR video editing. We then developed a prototype system implementing this new workflow. Our system is built upon a familiar timeline design, but is enhanced with custom widgets to enable intuitive editing of spherical video inside the headset. We conducted an expert review study and found that with our prototype, experts were able to edit videos entirely within the headset. Experts also found our interface and widgets useful, providing intuitive controls for their editing needs.