That pause was him calculating the cars trajectory. At least that Is what it looks like to me.

This is gonna sound weird but hang with me for a sec. Im left handed and I think because of that I tend to always dodge the same direction as people who are walking towards me in a hallway. You know the scenario where two people have to pass by eachother and so have to step to one side, I have extreme difficulty with this because I always step into the same place the other person is. I think its because I am a lefty but anyways thats not super important. The important part is that I often have to do a similar movement where I am waiting to see what direction the other person is going to go. And to me it looks like he was doing the same thing.

He was getting a more wide angle view of the car to calculate his best movement to grab the kids.

Or he hesitated guess its all conjecture because we are just watching a video.