I saw the video of speedrun where the regulation of brightness was on the main menu screen not in the options screen. How can I do that

https://drive.google.com/open?id=1tFO9i5WyNJbHgt4olsmXH4AjmSZUxXTr

Go into your options menu, click and hold the brightness slider (make sure that if you drag your mouse the slider actually moves), hit escape to go back to the game, release the brightness slider, hit escape to go back to the main menu, click the screen

thanks, it worked :3