On all routers except R4

R1#sh run | b ip mu
ip multicast-routing
ip cef
!
interface Ethernet0/0
 ip address 17.57.100.1 255.255.255.0
 ip pim sparse-dense-mode  <----------------- on all interfaces on all routers except R4
 half-duplex
!

R4#sh run | b ip mu
ip multicast-routing
!
interface FastEthernet0/0
 ip address 180.40.7.130 255.255.255.224
 ip nat inside
 ip pim dense-mode
 ip igmp join-group 224.4.4.4
 duplex auto
 speed auto
!