That certainly reduces the danger, though it does not determine who is at fault (if anyone), and is not enforceable in practice.
Sorry, I maybe wasn't clear - I was saying that we *shouldn't* say that both players have to do the same thing - I agree that it couldn't be enforceable.
Would a guideline automatically favouring the non-jumper be better? It would presumably discourage jumping, but the catcher is then vulnerable as the chaser is moving fast.
I expect it would be better, yes - it wouldn't encourage a chaser to jump into a standing player and milk a penalty - but I think not pre-deciding to favour either party would be best. And it might result in the situation where chasers stop going for the ball and prefer to just smash the catcher.
The current approach seems to be that if both players jump it reduces the danger without bringing in a new law.
I'm not sure it does reduce the overall danger. I can see that it reduces the danger for the guy who jumps higher, but increases it for the other guy. And as others have pointed out, it encourages unnecessary jumping from well-positioned players.
The initial video is unusual both in that the catcher jumps and the chaser does not, and that the chaser gets knocked out. The catcher was not jumping in a dangerous way - it was his hip that caught the opponent.
Agreed - I don't think there was any foul play there. The only stoppage should have been due to the injury, then restart with a scrum.