VideoTrim
VideoTrim[video,t] returns the first t seconds of video.
VideoTrim[video,-t] returns the last t seconds of video.
VideoTrim[video,{t1,t2}] returns video starting at time t1 and ending at time t2 of video.
VideoTrim[video,{{t11,t12},…}] returns a list of video objects for all given intervals {ti1,ti2}.
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