The video player is a fairly straightforward panel, it lets you select the video that will play on the VIDEO scene and tracks its progress. Videos to be played on the scene can be uploaded to the Videos section of the Assets menu, or placed directly into the assets\stuk-nodecg\videos folder. More details on the use of video files can be found in the Assets Guide.
Selecting a video from the dropdown list will ready it on the video graphic. The next time the video graphic is loaded, the selected video will play from the start and you'll be able to track its play time. It should be noted that the play time is retrieved from the live browser source, meaning having the video graphic open in multiple browsers will break the play time viewer. Selecting a new video from the list whilst one is already playing will cause the current video to stop and the new one to start.
Ticking INTERMISSION ON END will tell OBS to transition to the INTERMISSION scene when the video has less than 1 second of play time remaining. Leaving this unticked will freeze the video on the final frame when it ends.
On the right of the play time viewer is a restart button. This will immediately restart a video being played.
Because the graphic needs to refresh when it's loaded in order to play the video from the beginning, its important to have "Refresh browser when scene becomes active" ticked in the Video Browser Source's properties on the Stream OBS. This is set by default, but if you find videos aren't playing from the start, this not being ticked is likely the cause.