The present invention discloses methods for detecting, indexing, and comparing video signals from a video display in a background scene using a camera-enabled device. Methods include the steps of: pointing a camera-enabled (CEN) device at a video-signal surface; detecting a location of the video-signal surface in the background scene on the CEN device; and extracting at least one frame from the detected video-signal surface. Preferably, the method further includes the steps of: obtaining at least one image from at least one extracted frame; computing at least one compact signature from at least one image; comparing at least one compact signature with at least one stored compact signature in a database; and determining whether at least one match was found between at least one compact signature and at least one stored compact signature.