A Layer 3 switch does what a Layer 2 switch does and also routes traffic between subnets at high speed. That lets a camera VLAN talk to a recorder VLAN without sending every stream through a firewall or a small router, while keeping the two networks logically separate.
Segmentation is only useful if the segments can still reach what they need. The Layer 3 switch is the device that makes that possible without flattening the network.
Routing between camera VLANs
Each VLAN gets an interface on the switch, and rules decide which subnets may reach which. Video stays inside the building while administration reaches it deliberately.
When a router is still right
A Layer 3 switch handles internal routing. A router or firewall still owns the internet edge, remote access and the security policy that governs both.