Layer 2 Or Layer 3 Type Switch As Core Switch For IP Video Surveillance Network

As the simplest level, it would be hard to refer to any layer 2 switch as a "core" switch because of its lack of routing and control features.

That being said, if you had a standalone, flat (1 subnet), video only network, there's nothing that a layer 2 switch can't do to make the system function. (but I still would struggle to call it a "core" switch without routing capabilities)

In a mixed network usage environment, or complicated video network deployment, Layer 3 switches give you routing-functionality which will allow you to pass traffic between VLAN/Subnets, and potentially better control of broadcast traffic. Layer 3 switches also handle multicast traffic routing in a more efficient manner, if that matters to you.

Have been wondering myself about this. We are thinking about using a layer 2/3 smart switch that can create & monitor vlans, switch ports off and on all with remote capabilities.  Currently we use separate networks for building systems and do this thru the SonicWall .  but this is limiting. 

It really depends on the scale of the project or the number of services - If you need routing (or multicast routing) then you will need a L3 switch. In reality the lines are pretty blurry - all but the cheapest managed switches from the tier 1 providers will have at least static L3 functionality.

The terminology is often thrown around too much.

How big is the project? Is it purely CCTV? What switches are you looking at?

One rule of thumb, you will know you need Layer 3 functionality right after you install the Layer 2 switch.