I've done some reading and I do understand what it is but what I do not understand is how it is used in IPTV world and what is the advantage or disadvantage over unicast.

So I tried understanding multicast concept in a very simple iptv set up: e.g.
1. Head end providing 2 channels
2. Some middleware
3. STB

From my understanding, Unicast will stream the channels to a port and then you can simply define the link in middleware ( and watch the channel on STB.

How does this all work with multicast?