—In this paper, we consider two popular peer-to-peer TV (P2P-TV) systems: PPLive, one of the today most widely used P2P-TV systems, and Joost, a promising new generation application of which no previous measurement study has been considered. Besides the traditional measurements like the amount of generated traffic for signaling and data transmission, the novel contribution of the paper consists in investigating the content distribution mechanisms. In particular, we evaluate the characteristics of both data distribution and signaling process for the overlay network discovery and maintenance. By considering two or more clients in the same sub-network, we observe the capability of the system to exploit the locality of peers. We also explore how the system adapts to different network conditions. The methodology we develop allows also to identify periodic behavior of the application, highlighting bursts of both data and signaling traffic.