Ok this should be simple and straight forward.

/ip firewall mangle
chain=prerouting action=mark-routing new-routing-mark=facebook passthrough=n>
in-interface=Users-br-6-10 content=facebook

basically we are looking for packets that contain the work "facebook" and mark routing for them

then in

/ip route

New route set to 0.0.0.0/0 with gateway being the "special route vpn connection" and selected "marking route=facebook" from the mangle above.

but it doesnt work. it keeps routing the packets through the regular gateway.

pls advise.