PBR routing scenario for Firefox's windscribe plugin

[wellloaded]

I'm using the firefox extension (no thick client) for windscribe.

My router though is capable of MultiWAN/split tunneling/Policy based routing and that how I would like to handle my split tunneling for the dual WAN the router handles.

Q: How can I capture the traffic from Firefox's woindscribe plugin only? I suppose I could Policy Base Routing based on where the Firefox extension connects. Any tip on how to find the target FQDN/IP where the browser is connected so that I can feed this info to the PBR config on the router?

Thanks