A computer-implemented method of generating a video stream recommendation comprises identifying a plurality of peripheral devices monitoring zones of a physical area, the peripheral devices comprising a plurality of video cameras providing video streams of at least some of the monitored zones. The method further comprises querying a knowledge graph representing the peripheral devices and the monitored zones as ontology entities connected by edges representing physical paths between the monitored zones, and by edges representing which monitored zones the peripheral devices monitor, in order to identify a set of one or more video camera(s) monitoring zones other than a selected monitored zone, as a result of the querying. The method then comprises generating a video stream recommendation based on the result of the querying.