In terms of configuring firewalls/etc, it really depends on your equipment, however in most cases there's already a catch-all rule to allow any established & related traffic so you only need to add a rule to allow the initial connection establishment from LAN->TV.
> since you seem to imply it's different than searching about VLANs since it's wireless.
When it comes to VLANs, the idea is that the Ethernet port of the TV should either be connected to a managed switch that will tag any incoming traffic on that port with a VLAN tag before sending it upstream to your router (so it can tell what it is, since at that point it'll be arriving via a port that also has trusted LAN traffic), or connect it directly to the router and have that router's port not be part of the LAN bridge.
You don't have VLANs in wireless, instead you just create a new network - however the access point itself will need to either tag all traffic from said network with a VLAN tag (so again your upstream router can differentiate between that and trusted LAN traffic arriving over the same port), or if the AP is incapable of VLAN management then dedicate it to the TV network and connect it to a managed switch or dedicated port on the router as described above.
Meanwhile, do the VLANs allow the "enumerate devices" style multicast to come down from the regular LAN and be responded to?