Mikrotik RouterBoard + Ubiquity + multicast - how to set up?

Question

network hardware

Hello dear!
There is a scheme:
Rostelecom (ADSL) - Mikrotik RouterBoard RB750GL - AirGrid M5HP (1) - (wireless bridge) - AirGrid M5HP (2) - (ethernet) - Rocket M2 - many Wi-Fi clients.
In addition to the Internet, one client connected directly to the RouterBoard watches IPTV. He is the only one who sends requests for the service. The problem is that when he watches TV, the multicast (UDP?) stream scatters all over the network and reaches Rocket M2. I don’t know why it doesn’t fly further, but thank God. This flow significantly loads communication channels. Although the Multicast Data: Allow All checkbox has been unchecked since the first AirGrid.
How to prevent traffic from passing further than the first router (on it or on AirGrid'e)?

Answer 1

It doesn't fly further because in Rocket regular Linux, /proc/sys/net/ipv4/conf/eth0/rp_filter is enabled by default.

Answer 2

igmp snooping?

Answer 3

And in order not to fly multicast, put on the edge ACL on an unnecessary port.