The widely used, free to download video player, VLC Media Player has an odd quirk. Its default settings will flash the media title after the video is first opened.
This title will disappear after a few moments whether pause is pressed or not, but it can obscure closed captions or other text or images on the video. This will be an unpleasant surprise when video files are shown at a trial as evidence, or as a visual aid at client meetings.
Under Tools . . . Preferences, be sure to uncheck 'Show media title on video start'. Note that the media title will not necessarily be the same as the file name.