Hello Ruben,

the only possible issue comes from IGMP snooping that is enabled by default on Cisco switches.

When a router is missing in a Vlan where IGMP snooping is active you have two options:

a) you disable igmp snooping for that vlan, multicast traffic will flow out all ports of the vlan that can span on multiple switches (you need to disable on all of them)

on all switches:

no ip igmp snooping vlan M

b) if supported only one device has to act as IGMP snooping querier : that is it has to send periodic IGMP queries so that all switches can build a table that says what users have interest in receiving group G1, what users want to receive group G2 and so on.

C3560 supports it.

see

https://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_44_se/configuration/guide/swigmp.html#wp1055584

int vlan M

ip address x.y.z.k

no shut

exit

ip igmp snooping querier x.y.z.k

where M is the vlan of interest, x.y.z.k is an ip address of the IP subnet used in vlan M that the switch will use as source of IGMP queries.

Hope to help

Giuseppe