There are three modes
Playback mode: all persons are detected (this is the default mode)
Person search mode: the selected person is searched from played videos
All persons search mode: search all persons, try to display the same person only once
Found persons are shown in a thumbnail list. There are separate lists for all persons and selected person search results.
Thumbnail mouse click (or Enter key) shows the thumbnail location in the video
Thumbnail mouse double click opens the thumbnail video playback in the new tab