The BIS functions call BIS_fnc_playVideo and call BIS_fnc_customGPSVideo have never had the functionality to terminate the video sound and video image at any given moment, you can only cut the image of the video by using [] call bis_fnc_rscLayer) cutText ["","plain"]; which cuts the video image but doesn't actually stop the video from playing and as a result of this you can still always hear the sound of the video until the video stops playing. This is ridiculous and impractical and also ruins two great game function features.
This is a request to have a new script command or the functions changed to allow for the video to be properly terminated at any given moment instead of just the video image being cut. The community have asked about this in the past and nothing has ever been done about it.
I personally really think that if this is done the functions would be a nice feature for the new Arma 3 game and definitely used more commonly in community made missions. As it is you can only use very small sized videos because when played in game using these two functions you know that the video has to be played right to its end. Larger videos could be used if there is the option for the player to at any time be able to terminate the video, how it is now, once you've committed the video to play it has to be played to its end because there is no way of terminating the sound.