Back-end content analysis system to initiate second-screen confirmation

Particular embodiments provide a hybrid approach to confirming a presence of the second-screen device in a same location as a first-screen device. In one embodiment, a trigger phase and a confirmation phase are used to confirm the presence of the second-screen device in a physical proximity to the first-screen device. The trigger phase may be performed at a back-end system. The back-end system may detect events for the content being delivered to the first-screen device using content detection techniques. The back-end system may generate a trigger event when certain conditions are met based on the detection. Once the trigger event is detected, the back-end system may confirm that the second-screen device is physically present in a same location with the first-screen device. For example, the back-end system may communicate with the second-screen device to initiate a content detection analysis on the second-screen device.