This white paper compares the implementation of IP Multicast in the Cisco IOS and in the Nexus OS and provides some background on the evolution and challenges of implementing multicast in the IOS.
While there are differences between the IP Multicast configuration in the IOS and the Nexus OS, the Protocol Independent Multicast (PIM) protocol remains fundamentally the same. If you feel comfortable configuring Multicast in the IOS, you should be able to acclimate fairly easily to the changes in the Nexus OS.