Doh! Think it was my modem all along; when I hooked up the modem to my PC i noticed it had a *LAN* ip of 192.168.2.1 it also seemed to have its own igmp proxy.
- I set the modem to 192.168.99.1/24 so it didnt clash with any of my LAN(s) in the future
- I flashed the modem to "3.7.4BT" firmware (even though it was on 3.8.4 or something, the release of the BT one was April '16 - the newest)!
- I did "ip igmp-proxy set" on the modems console
- i set eth0 to upstream again on the ER and also gave eth0 192.168.99.199/24
And the TV started blurting out the white trash that live in Alaska; time to change the channel!
Hopefully anyone else trying to get iptv to work on the draytek might find this useful, lol!
The only issue now is that switch0 gets all the multicast traffic rather than just eth2 but I need to leave it to record motogp now...