The various embodiments described herein include methods, devices, and systems for categorizing motion event candidates. In one aspect, a method includes receiving and processing video frames that include a motion event candidate. The processing includes: (a) obtaining background factors corresponding to a background in at least a subset of the video frames; (b) utilizing the background factors to identify one or more motion entities; (c) for each motion entity, obtaining one or more representative motion vectors based on a motion track of the respective motion entity; (d) identifying one or more features in at least a subset of the video frames; and (e) aggregating the background factors, the representative motion vectors, and the features to generate motion features. The method further includes sending the motion features to an event categorizer, where the event categorizer assigns a motion event category to the motion event candidate based on the received motion features.