Bruce choreographed the screentest in that Trophy room. There're photos that show Bruce choreographed slim stuntman vs Wu Ngan, slim stuntman vs Wong Shun Leung. Brief Bruce's clip can be found in the Bruce Lee Man & Legend docu. Similarly, Bruce might have choreographed Wan Kam Leung doing Chi Sau with Wong Shun Leung. He might demo it to Wan how it should be done in front of the camera by doing Chi Sau with Wong first. Not sure whether there's footage on this.