All neurofeedback methods include EEG sensors that monitor your brainwaves, and a computer to send feedback back to you. There are different ways to receive this feedback. It can involve playing a game or watching a video.
The stimuli (game or video) only works smoothly when your brainwaves are functioning within an optimal range. This acts as a reward for your brain. When your brainwaves fire at a rate that is not optimal, you will receive negative feedback (your movie pauses, the music stops, etc.). This tells your brain that something is out of balance and causes it to “figure out” how to return to a seamless movie, music, or game.