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 (the bar is visual only, you can't seek using it). You can restart the current video with the button on the right.
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.
The "On end" section gives you some options for what to do when the video finishes, all triggered when the video has just under 1 second of run time remaining:
INTERMISSION ON END will tell OBS to transition to the INTERMISSION scene. Leaving this unticked will freeze the video on the final frame when it ends.
ADVANCE RUN PLAYER will tell speedcontrol to advance to the next run in the schedule. This is useful if the video you're showing has been included in your run schedule
STOP RECORDING will tell OBS to stop locally recording. Whilst triggered at less than one second, it has an artificial delay of 3 seconds so that the recording captures the whole video and the transition animation.
Because the graphic needs to refresh when it's loaded in order to play the video from the beginning, it's 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.