  Video summaries or highlights are a compelling alternative for exploring and
contextualizing unprecedented amounts of video material. However, the
summarization process is commonly automatic, non-transparent and potentially
biased towards particular aspects depicted in the original video. Therefore,
our aim is to help users like archivists or collection managers to quickly
understand which summaries are the most representative for an original video.
In this paper, we present empirical results on the utility of different types
of visual explanations to achieve transparency for end users on how
representative video summaries are, with respect to the original video. We
consider four types of video summary explanations, which use in different ways
the concepts extracted from the original video subtitles and the video stream,
and their prominence. The explanations are generated to meet target user
preferences and express different dimensions of transparency: concept
prominence, semantic coverage, distance and quantity of coverage. In two user
studies we evaluate the utility of the visual explanations for achieving
transparency for end users. Our results show that explanations representing all
of the dimensions have the highest utility for transparency, and consequently,
for understanding the representativeness of video summaries.
