Indeed very nice reaction from Jean De Villiers, but I think Alesana Tuilagui is not fully commited in the tackled as he saw the ball bounce off. So red is a bit harsh and a suspension would be too much, imo.
I think there are too many dangerous tackles in the try area : shoulder charges, swinging arms, dives on a player who is already on the floor, ... It is hard to define a clear limit, but those kinds of faults which are worth at least yellow cards are never punished. Moreover, when you are going to score a try, you are more vulnerable than usual (arms extended, legs not supporting your weight). I've been hurt at the ribs like that, even at a very low level. So i'm glad this player gets cited, and I hope things are now going to change.