Hi,
Did you have a look at XORP http://www.openbsd.org/4.3_packages/sparc64/xorp-1.4p1.tgz-long.html ?
Yes I had but there was no IGMP Proxy functionality. It was on the TODO list though.
So, your linux box is not involved in none-IPTV traffic via VDSL?
It just does Multicast Routing / IGMP proxying, announces the few nets that have to be routed via Vlan8 dynamically and firewalls itself with user unfriendly IPTables ;)
On a sidenote, I would order the cheapest IPTV VDSL offer. The others have a bandwith limit once you exceed a certain threshold. Have a look at the AGB.
Cheers Tobias