The value of tmnxVdoIfMcastProtocol indicates the multicast routing
protocol where this video interface is configured. For video control
and data traffic to flow correctly to the video ISA, the video
interface must be configured in the corresponding multicast routing
protocol.
In the VPLS case, the video sap is automatically added to IGMP-snooping
and so the value of this object will be set to 'igmpSnooping'.