The I/O interface to one or more clients 216 facilitates the client facing input and output processing. The account database 214 stores a plurality of profiles for reviewer accounts registered with the video processing server, where a respective user profile includes account credentials for a respective reviewer account, and one or more video sources linked to the respective reviewer account. The I/O interface to one or more video sources 218 facilitates communications with one or more video sources 222 e. g. , groups of one or more cameras and associated controller devices. The video storage database 210 stores raw video data received from the video sources 222, as well as various types of metadata, such as motion events, event categories, event category models, event filters, and event masks, for use in data processing for event monitoring and review for each reviewer account. Examples of the one or more networks 162 include local area networks LAN and wide area networks WAN such as the Internet. The one or more networks 162 are implemented using any known network protocol, including various wired or wireless protocols, such as Ethernet, Universal Serial Bus USB, FIREWIRE, Long Term Evolution LTE, Global System for Mobile Communications GSM, Enhanced Data GSM Environment EDGE, code division multiple access CDMA, time division multiple access TDMA, Bluetooth, Wi Fi, voice over Internet Protocol VoIP, Wi MAX, or any other suitable communication protocol. In some implementations, the server system 164 is implemented on one or more standalone data processing apparatuses or a distributed network of computers. In some implementations, the server system 164 also employs various virtual devices and/or services of third party service providers e. g.