In this paper we study these problems by analyzing a month-long trace of 15M accesses to BBC iPlayer in London. Our results show that up to 80% of server traffic can be saved by employing peer-assistance even despite the obstacles. Particularly, ISP-friendliness has insignificant impact on the traffic savings as the majority of user accesses come from a small number of large ISPs. Similarly, most of users watch content in one of two most popular bitrate formats. On the other hand, partial participation can significantly reduce the benefits of peer-assisted content distribution. To drive intuition, we develop a simple analytical model which links traffic gains from peer-assistance to the average number of users in peer-to-peer swarms, i.e., capacity of the swarms, and show how various obstacles impact the capacity. We also investigate the impact of two well-known techniques for improving content availability on the traffic gains and show that bundling is not effective in this context, however, a simple caching approach can boost the gain from peer-assistance for up to 30%.