You get two public IP addresses for every Telus account. You can switch the Actiontec into bridged mode, connect your router to one LAN port and connect your Optik TV box into another LAN port. This lets the Optik TV box bypass your routers LAN network and gives it direct access to the internet. In this configuration you don't need to worry about multicasting/IGMP Proxy settings.
Here's a pretty good explanation of IGMP Proxying.
Downsides to this setup configuration is that you don't have control over the overall bandwidth used between your TV Box and router network. This may be an issue if your network is regularly congested (maxed-out bandwidth) on your router LAN and you're trying to watch TV at the same time. This is normally handled gracefully when the Telus TV Box is inside your LAN by Quality Of Service (QOS) settings on your router. These QOS settings are set by default on the Actiontec. While in theory this is a downside I haven't noticed any issues.