We were working on enabling multicast over our wireless network. We were struggling with getting the end points to communicate. After talking to Cisco TAC and another wireless specialist we were told that we needed to enable pim on the access vlan of the AP's.
After testing this it does solve the issue but I want to understand why I needed to do this. When I tested multicast across our wired vlans off of the same switch gear we did not have the same issue.