The witness is a quality of our being. It is known as awareness, mindfulness. It is the non-judgmental observer of all our experience. It has been likened to the sky. Our thoughts, feelings, emotions, experiences etc are like clouds, weather, sun, moon, stars, and birds. They move through the sky but are not the sky. When they have passed the sky remains, unchanged. Usually we become so identified or attached to these things we forget we are the sky. Being the witness is to realise you are the unchanging sky.
Give yourself a full 25 minutes to explore this practice. Make sure you won’t be disturbed and have room to dance in. Hit play and follow the guided dance.