Well the ones that stream live should be detectable by either sniffing wifi traffic or tracing the Ethernet cables. If they're not battery powered they should a

Well the ones that stream live should be detectable by either sniffing wifi traffic or tracing the Ethernet cables. If they're not battery powered they should also be plugged in the mains somewhere, but not sure how you'd find them easily. If they're battery powered and record to internal memory then you'd probably need to spot them directly.