How does the elimination process work on this show, and do they show it on TV?

It's just the judges seem to be letting so many, what seems like hundreds, of acts through each week, it would take forever to show them each again and then filter them down. How long is this show on for?

Btw, I always get so annoyed when some cute little boy or girl goes on, because the judges always say 'awwww' and you just know they'll always let them through just by virtue of them being young and cute. Don't mean to be an evil old grinch, and of coure it takes so much courage to go up there so they should always be as polite and nice as possible, it's just getting boring because it's so predictable. Is letting such young children on the show really appropriate?

And related to my question above, i was thinking they'll have to reject these little sweethearts at some stage won't they (i mean there's only one winner)

...do they do this behind the scenes somewhere and then just suddenly show the semi finals and then finals??

At the end of next weeks show, it'll show the judges in a room, cutting down all the acts they've let through until they reach 40. No re-auditions or boot camp or anything. So yes, it's all behind the scenes for the most part

And then hey ho, it's the semis!