The push into the camera was perfectly fine, they were both chasing the ball and its a contact sport. The south african guy was between him and the ball, and therefore is fair game for a shove in an attempt to get it. If it was to bounce backwards, or to the side then a try would have been on the cards and he was entirely within his rights to get himself access to the ball.
Montgomery may not have done much while remaining on the pitch, but they had the option to replace him, and it was still 15 men. Seeing as many RWC matches have descended into "tactical kicking" he basically did as much as he would have done anyway.
Ill assume that by your 6nations comments your referring to me, yet you don't dare address me directly. Considering its the younger players who won't be quitting that have the "gelling" issues im sure this team will be more than ready and fired up for the 6nations. Id make some comment about how great it would be to obliterate Wales in the tournament, but then everyone else gets to do that as well, even Italy probably have a decent shot.