Well, even though I didn't take this, I thought it would be worth posting. This video shows the fans entering the field after Wisconsin's victory over Ohio State.
This shows how the fans entered the field in lines instead of a mass swarm from all directions at once. For this, massive props are due to the Madison Police Department and Camp Randall Stadium security forces. The only known injury was a sprained ankle.
This is in stark contrast to a 1993 game against Michigan, when dozens of students were injured, some critically, when fans tried storming the field only to run up against guardrails. Here is the only video I know of about the "Camp Randall Crush".