1. A computing device configured for performing a set of acts for outputting an alert indicating a functional state of a back-up audio-broadcast system, the set of acts comprising: receiving, by a computing device, a first video-stream that represents first video-content; generating, by the computing device, a first signature based, at least in part, upon an extent of scene-change transitions included within the first video-content, wherein the first video-stream was generated by a primary video-broadcast system; receiving, by the computing device, a second video-stream that represents second video-content, wherein the second video-stream was generated by a back-up video-broadcast system; generating, by the computing device, a second signature based, at least in part, upon an extent of scene-change transitions included within the second video-content; making, by the computing device, a determination that the generated first signature and the generated second signature lack a threshold extent of similarity; and responsive to the determination that the generated first signature and the generated second signature lack the threshold extent of similarity, outputting, by the computing device, an alert indicating that the back-up video-broadcast system is not functioning properly.