Sighthound Video tracks people. It can also be given specific rules, such as record a clip when a person walks through a doorway. There is a very powerful, yet easy to use intelligent video search capability. You can even look for certain times on certain days to see when people arrived or left.
Late one evening there was a fire at the Sighthound office in Orlando. We quickly searched the Sighthound Video feed from our office and counted that everyone was safely out. We also watched the firefighters doing a fantastic job of searching the building and putting out the fire.