A Layer 2 switch moves frames between ports on the same network using MAC addresses. It does not route between subnets. In camera systems it provides the ports, the PoE budget and the VLAN separation that keep video traffic organized and away from business data.
Most camera networks are built from Layer 2 switches. Their specifications, not the recorder, usually decide whether a camera drops off the network.
What the switch decides
It learns which MAC address sits on which port and forwards frames only where they need to go, which is why a busy camera does not flood the whole network.
Features that matter for video
Check the PoE budget, whether VLANs and IGMP snooping are supported, the uplink speed, and the operating temperature if the switch lives in a plant room.