The most successful P2P delivery method today is the substream method, which is a major improvement on the traditional BitTorrent-based delivery yet still suffers from the need to use fixed-size pieces. Such a delivery creates situations when user's social utility during streaming is a gamble based not only on own networking environment but also on that of parent nodes. This paper shows how variable bitrate (VBR) formats can support alternative substream designs that effectively sever the downstream proliferation of quality impairment.