Andrew is correct; however, the protocol they use is Bonjour, which is predominantly a Layer-2 protocol. My understanding is that it does Multicast to 224.0.0.251
Is your WAN a stretched VLAN? I would not expect this to be an issue across a routed network unless you are running something like PIM
https://en.wikipedia.org/wiki/Protocol_Independent_Multicastip access-list extended blockAPLTV
sequence 10 deny udp any any eq 5353
sequence 20 permit ip any any
On your WAN port (i.e. your VE interface)
Interface ve 100
ip access-group blockAPLTV in