I am trying to get multicast set up on my Mikro, now I can setup PIM easily enough, but the log gets flooded with errors asking for an RP. My question is what should I setup? I only have the 1 mikrotik and 3 vlans. I am only forwarding multicast between two of the vlans. Any suggestions?
Better late than never 
I do have two routers but only one to forward multicasts so far. Strange enough RouterOS lets you configure igmp without PIM but this does not seem to work even for a single router (i.e. useless).
RouterOS appears only to support sparse-mode PIM (which is OK) which requires a rendezvous-point (RP). With a single router you need to configure one of the interface addresses of that router (best one participating in the multicast) as RP, which is done under Routing->PIM->RP, where you simply set the address and keep the other field to their default values.