With snooping on multicast isn't flooded unless the destination address is in the 224.0.0/24 range. To get any other multicast to go out the listener needs to send an IGMP report stating that it is interested in the group. A listener will do a gratuitous report once when it starts up, after that it will only send a report in response to an IGMP query.
I'm guessing you don't have multicast protocols (pim/igmp) running on the vlan. There needs to be something in the broadcast domain(s) sending out the necessary IGMP query. If PIM is enabled for multicast routing, IGMP is automatically enabled as well. If this is just local though you don't really need PIM. You could enable IGMP directly if you have an L3 interface in the broadcast domain(s). Finally, the last option is you could enable the l2-querier option inside igmp-snooping. If it is a pure L2 domain without any L3 interface that's the only viable option.
set protocols igmp-snooping vlan <blah> l2-querier source-address <some_address>
You can use any address you want for <some_address>, the switch just needs some IP address to put in the source IP field in the IGMP query packet.
Oh, and beware of using "vlan all" in igmp-snooping. You can try it, but more often than not it doesn't work. It's safer to specify the vlan name(s) instead.
-Chad