I think OSU actually picked up that fourth down, but they did it illegally and didn't get flagged.
NCAA Rule: "The ball carrier shall not grasp a teammate; and no other teammate shall grasp, pull, or lift the ball carrier to assist in forward progress. (A.R. 9-3-2-I)"
So there is justice there.
Thanks, I had thought that at the time. You can push but not pull like that lineman was doing. In a big scrum at the goal line it's hard to tell but that was just the big guy in clear view doing it.