Windows Server Essentials in a 100 employee company?

Welcome to everyone's favorite Microsoft gameshow, *Explain That License!*

So, here's the situation I find myself in. We are a ~100 employee company running our domain on Windows Standard servers. I'm looking to purchase a new server that will act as an NVR for our security camera system.

Some of the NVR software packages we're evaluating run on Windows. We're not married to any of them at this point, but we are trying to determine TCO verses some of their *nix-based competitors for a true apples-to-apples comparison.

The number of employees who would actually need access to the security camera system is <10 and not expected to ever significantly increase, so my initial thought was that Server Essentials might be a more cost effective option for this specific device.

Would purchasing a Windows Server Essentials license for this one server A) be allowed in our situation B) make sense for our purpose?

I've never used the product so I don't really know how nicely it plays with its bigger siblings or if there's some gotcha clause in the licensing agreement that makes it a non-starter for a business of our size.

Any input would be appreciated.