I was in a Sydney newsagency yesterday with 16 cameras monitoring the shop and a screen at the counter for watching.
The other, and probably more important, benefit of the screen is to show customers the store is monitored.
The more a person thinks they are likely to be caught the less likely they are to steal from a business (or home). St least that is what police have told me. hence the value of the screen at the counter showing the live feeds from the sixteen cameras.
With camera systems costing far less today than a few years ago, they more quickly pay for themselves as deterrents with this type of counter placement of the screen and with obvious placement of cameras in-store.
With theft costing between 3% and 5% of product revenue, investing in a deterrent is important, it provides a good return.
A side benefit of good camera coverage of the store is the ability to watch shopper traffic and learn from their interaction with displays. I find it particularly useful to fast-forward through footage to learn from customer actions in the business. The insights are valuable.