I'm not familiar with the capabilities of BRS so unfortunately cannot comment. But as an analytics sceptic since 2007, and having toyed with different systems including Iomniscient, Delopt, Allgo Vision, and ISS, we have settled to proposing only Ipsotek (UK) and iCetana (Australia) to our customers sometimes in combination. Mostly because Ipsotek is rules based and iCetana automated.
Frankly to date we still treat analytics as a value add to the overall security infrastructures we deploy. If you are interested in knowing more about iCetana, I can put you directly in touch with their Australian sales rep. I'm sure they would be happy to provide you with a demo unit for trial purposes. We have deployed their server on 3 different sites to date, and on all 3 sites (2 hotels, and a car dealership) it has performed.
The real question which I suspect is impossible to answer is "What is the system missing whilst analyzing the video streams?" I can only pass judgement on the alerts received of which most have some relevance to security and operations.
One last thought, in terms of use in the control room, I find it very effective from an attention alerting perspective. The fact that the screen remains blacked out and only on alerts does a video pop up in a cube, means the operator doesn't become overwhelmed with alerts and eventually disables the system or completely ignores it. The video disappearing after 45 seconds, yet still logged in the events list makes it a useful tool for even the laziest of control room operators.