Ok, in case you haven't seen the video, here it is.
So the ball is between the 44 and 45, Oklahoma State needs to get to the 34.5 yard line, penalties happen and we're in a third and 23 situation. Someone on the chain gang wasn't doing their jobs, so the referee thought the first down was where the down marker was on the field, on the 40. To see the yard marker, go to 2:36 or look below.
Here we clearly see Marcell Ateman has the ball at least a few yards ahead of the marker on the field.