Vidic broke the laws of 'the game' they are supposed to be adhered to, not overlooked when it suits. Fact, Vidic should have received a red card, even if he did not a yellow would have changed the game he would have be less affective and chances are we would have had more chances. I do believe he would have received a second yellow and been sent off any how.
Lets remember the laws of the game are part of the game, if you can't stick to them then the punishment is part of the game, to ignore this is naive, IMO.
Alex Ferguson, Mourinho, Wenger...... all know the importance of playing the ref. Its a hollow victory for Man U and a soul destroying defeat for us and more importantly the game of football.