This is the RowStatus for a conditional-filtering table entry, and per its description, creating a row with igmpCondFilterMcastMember set to true forces that group's traffic to be forwarded to that interface regardless of whether actual IGMP Membership Reports are being received. It gives an admin a manual override mechanism to force-forward a multicast group to an interface even when the dynamic IGMP snooping/membership detection would otherwise withhold it. Creating a row for group 239.10.10.10 on interface Gi0/1 with member set true would guarantee that stream reaches that port even if no host there ever sends an IGMP join.