  File sharing, typically involving video or audio material in which copyright
may persist and using peer-to-peer (P2P) networks like BitTorrent, has been
reported to make up the bulk of Internet traffic. The free-riding problem
appears in this "digital gift economy" but its users exhibit rational
behaviour, subject to the characteristics of the particular network. The high
demand for the Internet as a delivery channel for entertainment underlines the
importance of understanding the dynamics of this market, especially when
considering possible business models for future pricing or licensing regimes
and for the provisioning of network capacity to support future services. The
availability of specific titles on file sharing networks is the focus of this
paper, with a special emphasis on the P2P protocol BitTorrent. The paper
compares the incentives provided in BitTorrent to those in other file-sharing
communities, including file hosting, and discusses the number of titles
available in the community at any given time, with an emphasis on popular video
items with ambiguous legal status.
