This issue has to be taken more seriously. It was a joke Jeremy Cameron was able to keep playing and clearly its because Geelong were trying to win the game.
I like what this YouTube comment says:
Forget the Hamstring comparison - the better comparison is the 'Blood Rule'. If a player hits his head against another player - or hits the ground with his head - he should be taken off. That should be ordered by the umpire - then the player comes off the ground & the doctor can make a proper assessment. Like with the blood rule or another injury - he can be properly checked. Then the doctor can decide to let him on the field again - or not
You just have to come off if you hit your head. Simple as that. If the player doesn't come off then the club should be fined or a free kick given.