1. A method, comprising: at a server system having one or more processors and memory: while receiving video information from one or more cameras, the video information including a video stream: obtaining motion start information corresponding to a first time in the video stream, the motion start information indicating that a portion of the video stream subsequent to the first time includes a motion event candidate; while receiving the portion of the video stream that includes the motion event candidate, segmenting the portion of the video stream into a plurality of temporal segments, the plurality of temporal segments including an initial segment; obtaining a first categorization of a plurality of categorizations for the motion event candidate based on the initial segment; in accordance with the obtained first categorization, generating an alert indicative of the first categorization for the motion event candidate; obtaining motion end information corresponding to a second time in the video stream, the motion end information indicating that a portion of the video stream subsequent to the second time does not include the motion event candidate; in response to obtaining the motion end information, obtaining a second categorization of the plurality of categorizations for the motion event based on the plurality of temporal segments; determining whether the second categorization is the same as the first categorization; and in accordance with a determination that the second categorization is not the same as the first categorization, generating an updated alert indicative of the second categorization for the motion event category.