they not be compensated for the flow? If you are going to have N times receivers of your stream, should they then not have the ability to charge you some factor greater than 1 to support the flow? One method is to limit the amount of bandwidth of multicast per edge interface, but if a 128K stream is sent to hundreds or thousands of places then it could impact certain links as well. Maybe not the backbone running at OC-x speeds...
I'm relatively new to multicasting, but my impression is that if you have a 128K stream that you are sending out then, even if you are sending it towards hundreds or thousands of places, no individual link would have more than 128K on it (thus the point of multicasting). There may be hundreds of different links each with an additional 128K, but the N-factor amplification you are referencing would be more from the "we now have to send this same 128K out 20 different peering links and possibly (depending on your peering policy) pay 20 times the bandwidth cost" but it shouldn't cause any individual link to become overloaded. Eric :)