  Video consumption is being shifted from sit-and-watch to selective skimming.
Existing video player interfaces, however, only provide indirect manipulation
to support this emerging behavior. Video summarization alleviates this issue to
some extent, shortening a video based on the desired length of a summary as an
input variable. But an optimal length of a summarized video is often not
available in advance. Moreover, the user cannot edit the summary once it is
produced, limiting its practical applications. We argue that video
summarization should be an interactive, mixed-initiative process in which users
have control over the summarization procedure while algorithms help users
achieve their goal via video understanding. In this paper, we introduce
ElasticPlay, a mixed-initiative approach that combines an advanced video
summarization technique with direct interface manipulation to help users
control the video summarization process. Users can specify a time budget for
the remaining content while watching a video; our system then immediately
updates the playback plan using our proposed cut-and-forward algorithm,
determining which parts to skip or to fast-forward. This interactive process
allows users to fine-tune the summarization result with immediate feedback. We
show that our system outperforms existing video summarization techniques on the
TVSum50 dataset. We also report two lab studies (22 participants) and a
Mechanical Turk deployment study (60 participants), and show that the
participants responded favorably to ElasticPlay.
