1. A surveillance system for detecting a fall risk condition, the system comprising: a surveillance camera configured to generate a plurality of frames showing an area in which a patient at risk of falling is being monitored; and a computer system comprising memory and logic circuitry configured to: store motion feature patterns that are extracted from video recordings, the motion feature patterns are representative of motion associated with real alarm cases and false-alarm cases of fall events; receive a fall alert from a classifier, the fall alert associated with the plurality of frames generated by the surveillance camera; determine motion features of one or more frames from the plurality of frames that correspond to the fall alert; compare the motion features of the one or more frames with the motion feature patterns; and determine whether to confirm the fall alert based on the comparison.