So, to get this straight. You have a routerboard which is configured as bridge. And this routerboard you are putting a simple queue which should control the bandwidth of a device which is not in its network, right?
Then, try in /ip firewall mangle to mark the packets coming from this device:
/ip firewall mangle
add chain=prerouting src-address=192.168.223.252 action=mark-connection new-connection-mark=IPcam passthrough=yes
add chain=prerouting connection-mark=IPcam action=mark-packet new-packet-mark=IPcam passthrough=no
You should see the counters on these rules running. If they are not counting it means the router is not capturing this traffic. If they are running, then use the packet mark in the simple queue instead of the target ip.
What router do you have before the bridge one? It should be easier to do limitation on that router.