1. A method of categorizing a motion event candidate, comprising: obtaining a respective motion vector for each of a series of motion event candidates in real-time as said each motion event candidate is detected in a live video stream, comprising: identifying at least one object in motion in a respective video segment associated with the motion event candidate; determining a respective motion track of the at least one object in motion within a predetermined duration; and generating the respective motion vector for the motion event candidate based on the determined respective motion track of the at least one object in motion; in response to receiving the respective motion vector for each of the series of motion event candidates, determining a spatial relationship, in a vector event space, between the respective motion vector of said each motion event candidate to one or more existing clusters established based on a plurality of previously processed motion vectors; and in accordance with a determination that the respective motion vector of a first motion event candidate of the series of motion event candidates falls within a respective spatial range of at least a first existing cluster of the one or more existing clusters, assigning the first motion event candidate to at least a first event category associated with the first existing cluster.