1. A method for multi-mode video event indexing, the method comprising: applying background subtraction to video input images from a video stream input to detect foreground object activity as a difference between current frame image information and static information of a contextual background of the video input images from the video stream input; determining by a processor a level of density of the foreground object activity detected with respect to the video input images from the video stream input relative to an entirety of the image; in response to the determined level of density of the detected foreground object activity meeting a threshold density value, the processor selecting from a plurality of video analytics modes and applying an object tracking-based analytic mode to the detected foreground object activity of the video input images to track a foreground object; and in response to the determined level of density of the detected foreground object activity not meeting the threshold density value, the processor selecting from the plurality of video analytics modes and applying a non-object tracking-based analytic mode to the detected foreground object activity of the video input images to determine object movement from extracted foreground object appearance attributes without tracking the foreground object.