I found the game highlights on YouTube. The play starts at about the 36:05 mark into the video, :54 sec game time. It is 3-9 for Marshall (green) from just inside the B45 yard line.
Marshall intercepted the ball and the interceptor was downed at the then A30 yard line. Marshall was penalized after the play 15 yards for USC and the ball would have been spotted at the now B45 yl.
Now if you want to argue that the Marshall receiver didn't get any part of the ball to the B35 yl, which would be all that he had to do as the ball would have been spotted with the nose on the B45 as any good NCAA umpire on down would do, then I'll grant you the argument there.
If your argument is he didn't get to the superimposed yellow line, that has nothing to do with it and is unofficial and would not have been the line to gain.
http://youtu.be/PZv9Y2a-AGc?t=36m5s