We don't have any record of Derren having taken a PhotoReading class. It's possible he used an assumed name or took a spin off course. Why he used the name PhotoReading I don't know. I venture a guess to say it's the similarity in the PhotoReading step where you make the mental snapshot of the pages while flipping them. Unfortunately there is more to the system and when you use the system you can get your reading done 3 to 10 times faster than traditional reading.
I found his video frustrating because it isn't what PhotoReading is about. The camera never actually showed text on the page. Tricks include what you don't see as well as what you do see. Notice the camera angle when you see the librarian you notice that there is no camera behind him yet when you see Derren you have his shoulder in the shot.
The librarian seems impressed perhaps because he saw the technique demonstrated differently.
Oh and finger licking gross. Think about it. It's a public library book how many people need to do that.
Alex