You're all going to hate me...

[Bluebird]

They could see a bit of the balcony, i.e. if an adult was standing on the balcony waving they'd see them.

This would help them only if the apartment was on fire! They certainly couldn't see into the apartment, which is where the kids were.

The picture was taken in broad daylight as well, not in the dark when the abduction took place - I doubt whether the apartment was floodlit..