Anyone? Or is this better to block at the core switch/router?
We have setup rules like this for instances where printers and the like spam multicast. It's pretty effective obviously depending on what you want to accomplish. I would say AP to wireless medium, it can definitely help channel utilization.
However, I would recommend IGMP snooping where possible in the LAN to prevent the AP from ever getting multicast if there are no members present. And then you could try the multicast rate optimization on the SSID to improve performance if clients actually need multicast.