Multicasting Dense Mode

I spent a good part of my morning working my way through the second multicast lab in the CCNP portfolio book the best I could. Since I didn't have a real switch that could emulate SVI (I don't think) I had to use GNS3 the best I could for the IGMP snooping. Multicast is by far the hardest topic for me so far and I still don't understand it honestly. I know enough to get by but it's still very confusing and works differently then any of the routing protocols. I did understand a little more about how the multicast tree is built however using other routing protocols are RPF (reverse-path forwarding). this will for sure be a topic I'll have to spend extra time on understanding, tomorrow is another multicast lab using PIM sparse mode instead of dense mode.