1. A method for outputting an alert indicating a functional state of a back-up video-broadcast system, the method comprising: a computing device receiving first closed-captioning data that (i) corresponds to a first video-stream generated by a primary media-broadcast system, and (ii) represents first text associated with a first time; the computing device receiving second closed-captioning data that corresponds to a second video-stream generated by the back-up media-broadcast system; the computing device making a determination that the received first closed-captioning data and the received second closed-captioning data lack a threshold extent of similarity, wherein making the determination that the received first closed-captioning data and the received second closed-captioning data lack a threshold extent of similarity comprises determining that the second closed-captioning data does not represent the first text associated with a second time that is within a tolerance period of the first time; and responsive to the determination that the received first closed-captioning data and the received second closed-captioning data lack the threshold extent of similarity, the computing device outputting an alert.