Abstract. We present a user-based approach for detecting interesting video segments through simple signal processing of users collective interactions with the video player (e.g., seek/scrub, play, pause). Previous research has focused on content-based systems that have the benefit of analyzing a video without user interactions, but they are monolithic, because the resulting key-frames are the same regardless of the user preferences. We developed the open-source SocialSkip system on a modular cloud-based architecture and analyzed hundreds of user interactions within difficult video genres (lecture, how-to, documentary) by modeling them as user interest time series. We found that the replaying activity is better than the skipping forward one in matching the semantics of a video, and that all interesting video segments can be found within a factor of two times the average user skipping step from the local maximums of the replay time series. The concept of simple signal processing of implicit user interactions within video could be applied to any type of Web video system (e.g., TV, desktop, tablet), in order to improve the user navigation experience with dynamic and personalized key-frames.