TimA:
Vodafone provision like this: 200Mb/s (download) 50Mb/s (Upload) 72Mb/s (Multicast for Vodafone TV)
which is quoted all around here, but does not explain why when streaming a multicast stream, there is a drop in downstream bandwidth.
thus shooting in a barrel to try to work out how that segregation is made, assuming its not a hardware imposed drop in performance.