How To Pass Multicast Traffic on an Extreme Switch

Extreme EXOS by default has IGMPv2 and IGMP Snooping enabled.
So as long as the multicast sender and receiver are in the same vlan multicast should work without a problem. 
Usefull command to see if the right ports are seeing the multicast streams sender and receivers is:
If the multicast traffic needs to routing between vlans you need a multicast routing protocol like for example pim or MVR.

MVR is very simple, you enable mvr on 1 vlan where the multicast streams are received, then any vlan that needs the multicast stream will forward it after it received a igmp join.
Pim can operate in dense mode or sparse mode.
In Dense mode multicast traffic is send to all vlans after which they are pruned if they are not needed.
Sparse mode works the other way, it only forwards multicast streams to the vlans/subnets that need these streams. 

Example pim dense mode (2 vlans, vlan vl1 and vl2)
Example pim sparse mode (same vlans)

Create a policy file describing the multicast groups you want to forward.
(This is for the RP, in this simple example the switch will be RP and BSR).

vi rpset.pol
entry rp-set {
 if match any {
 }
 then {
  nlri 239.0.0.0/24
 }
}

Some examples are in these links:
How to configure PIM sparse mode on EXOS
How to Configure PIM-SSM in EXOS
How To Configure MVR
How To Configure an S-Series and Summit to Route Multicast Between Each Other using PIM Sparse