That's not correct. Around 25% of the video is discussion around the concept of the radius of photon sphere to the event horizon, and what constitutes the light surrounding the photon sphere (one explanation he gives is that there are infinite reflections). Then he spends the last 30% of the video talking about reflections of the acretion disk. This is the theory that he never included in his original prediction, but doesn't explain why he made that call.