I love the suspense that is created with everyday actions. Kids sing and play about things like this all the time, for example Charlie Charlie is popular right now. It creates this struggle between real and imagined danger. Especially with the line if you can hear them singing their fine.
There is also a feeling of dred created with the silence and sound. Every time it got quiet I was waiting for something to happen then we get to the busy noises of the city and it almost puts you on alert.
I feel like the clip does a really good job of giving ypu a sense of waiting.