Look Back Rule - YouTube
Please take a look at :40 sec. In the context of the rest of the video, this is described as a violation of the LBR.
I see this as a play by the pitcher, and if the runner was between bases I'd definitely drop the LBR. Since the runner is on 1st at this point, I wanted to hear your feedback. Does a "play" (assuming you consider this a play) release the runner from the base?