Mesh-based P2P streaming approaches have been recently proposed as an interesting alternative to tree-based approaches. However, many properties of mesh overlays remain little understood as they are difficult to study due to the lack of a predefined structure. In this paper we show that when data is streamed through mesh overlays, it follows tree-based diffusion patterns and thereby mesh-based streaming can be studied in a similar manner to tree-based approaches. We identify properties of the diffusion trees that emerge in mesh overlays and compare them to optimal diffusion trees. We show that the emerging diffusion trees exhibit suboptimal height and are unbalanced, which results in increased buffering delay of mesh-based P2P systems, particularly in heterogeneous environments. We present an algorithm that adapts the mesh overlay to shorten diffusion trees and to reduce the buffering delay.