At the start of the second half, the recieving teams player that caught the kick off was clearly tackled 1 yard behind the chalked line. you see it from a couple of camera angles. When the ball is snapped, you can still see that they are one yard behind the line. Then when the ball carrier is tackeled the ball is shown to be 1 yard beyond the line and the ref says " second and nine " a gain of 1 yard. It should be second and eight with a gain of 2 yards.