Don't make assumptions about the proximity of the camera to the blast. There's a thing called "lenses." The physical camera could be several miles away. Also, as per periscopes in submarines, a camera could be underground and shooting through a series of mirrors to above ground.>>7744175
Notice the mushroom cloud in the background. Seems to be several miles away. If you've ever watched some of the military films of nuclear blast waves, you've seen various objects such as houses, ships, cars, livestock, forests, etc. as they are incinerated. The DoD placed a LOT of objects at various distances from ground zero (including soldiers) to watch, film, and evaluate how they were affected. Having weather balloons, smoke streams, and blimps in the sky help evaluate distance and altitude factors vs. damage suffered and travel of the different energy waves.