This is a strictly Newtonian view. The relativistic circular orbit equation includes a factor [1-2GM/(rc^2)]^(-.5) and it yields an orbital radius of 1.5Rs for light around a non-rotating black hole. For a popular (fun) account, see Prof. Kip Thorne's book "Black holes and time warps", 1994, Prologue, page 39. More technical info is available in many sources, e.g. Misner, Thorne and Wheeler's "Gravitation".

I'm actually quite surprised that Dr. Gay made this apparent mistake. Or am I missing something?