A client device accesses a video input stream from an intermediate device for display. The client device analyzes the video input stream to determine that the video input stream matches a template indicating a change of speed. In some example embodiments, the analysis is performed while the client device is generating a video output stream that replaces video content received from a content source via the intermediate device. Based on the video input stream matching the template, the client device modifies the video output stream to show the change of speed. For example, commercials transmitted from a national content provider to a smart TV via a set-top box may be replaced with targeted commercials. During the replacement, fast-forwarding of the commercial may be detected by matching a template with the video input stream. While the video input stream is being fast-forwarded, the smart TV fast-forwards the targeted commercial.