Authorship entails the constrained selection or generation of media and the organization and layout of that media in a larger structure. But authorship is more than just selection and organization; it is a complex construct incorporating concepts of originality, authority, intertextuality, and attribution. In this paper we explore these concepts and ask how they are changing in light of modes of collaborative authorship in remix culture. We present a qualitative case study of an online video remixing site, illustrating how the constraints of that environment are impacting authorial constructs. We discuss users' self-conceptions as authors, and how values related to authorship are reflected to users through the interface and design of the site's tools. We also present some implications for the design of online communities for collaborative media creation and remixing.