On the Interfaces & Routing > Multicast Routing (PIM-SM) > Advanced tab you can configure some advanced settings for PIM.
In some networks the PIM communication route between sender, RP, and recipient is not the shortest network path possible. The option Enable Switch to Shortest Path Tree allows to move an existing communication between sender and recipient to the shortest path available, omitting the RP as moderator, when a certain traffic threshold is reached.
With this option enabled, the system will automatically create all necessary firewall rules needed to forward multicast traffic for the specified multicast groups.
Select the option Enable Debug Mode to see additional debugging information in the PIM-SM routing daemon log.