I have photo and video libraries open, and I’ve used some of the files in my slide show. They show a badge when used. But WHERE are they used? At least photos show a thumbnail in the timeline and storyboard. Videos do not, and the generic movie icon in the timeline tells me nothing other than that it is video.
There ought to be a way to click on a used file in the library and have the program tell me the time stamp within the slide show, like a “Get Info” option on right-click or something. And perhaps even more important, to indicate the video file names when viewing the timeline or storyboard.