More information and a couple of pictures from Bat-mama:
Bat-mama @Tarryntino 49m49 minutes ago Melbourne, Victoria
@Plaidmoon it was in federation square, it was two men. I think they were wearing green tshirts :-)
11:32 PM - 3 Dec 2015
Bat-mama @Tarryntino 40m40 minutes ago Melbourne, Victoria
@Plaidmoon another 2 teams...
11:42 PM - 3 Dec 2015
It looks like they are working with a children's choir or something like that.


Not a children's choir. They had to gather 50 people from area (I am not sure where for the other groups, but the last one was on stage), and have them shout out something in Hebrew - I think it translated to something like "*name* and *name* are the greatest couple." They handed out orange shirts to everyone (for the group on the stage) - not sure why, possibly just to track numbers.
My daughter was just out of the photo on the right, and I was standing behind the group (children had to have a parent on stage).
It was all a bit strange - they were just running around begging people to go on the stage and shoving the t-shirts at them. No-one quite knew what was going on, or what the phrase they were telling us to say meant - I think everyone assumed it was some Christmas thing.

Then as soon as we had said it, they ran off and everyone was just left trying to work out what just happened, and what to do with the t-shirts! (We got to keep them, so now my tiny 10 year old has a bright orange mens size 4XL shirt

).