Once they see you, it's a game...
I've done this before with Chloe.. and it happens pretty fast. You have to imagine that Tucker (now almost 2) is ALWAYS moving. To get him in one place for 30 sec is quite a feat.

So I set the camera on the surface and held the button down... beginning to play peek-a-boo with him.

I got just enough before he was off and running again.