In some implementations, the server system 164 includes functional modules for an event processor 3146, an event categorizer 507, and a user facing frontend 3150. The event processor 3146 obtains the event candidates e. g. , by processing the video stream, by receiving the event start information from the video source 501, or by detecting a user press on a doorbell button of a doorbell camera. In some implementations, the event candidates include motion event candidates. It is noted that the video source 501 is an example of the video source 222 shown in FIG. 2B. In some implementations, the event candidates include a user press on a doorbell button of a doorbell camera. In some implementations, the event candidates include audio and/or visual aspects. The event categorizer 3148 categorizes the event candidates into different event categories. The user facing frontend 3150 generates event alerts and facilitates review of the events by a reviewer through a review interface on a client device 220.