Chapter 7 Firewall : Multicast forwarding : Multicast routing examples : FortiGate PIM-SM debugging examples : Viewing the kernel forwarding table
  
Viewing the kernel forwarding table
Also the kernel forwarding table can be verified, however this should give similar information to the above command:
FGT-3 # diag ip multicast mroute
grp=239.255.255.1 src=10.166.0.11 intf=9 flags=(0x10000000)[ ] status=resolved
last_assert=2615136 bytes=1192116 pkt=14538 wrong_if=0 num_ifs=1
index(ttl)=[6(1),]