This is a "video" that is interpreted from only a few (3-4?) still images of the Mt. St Helens blast. So part of it is "fake" to give you an idea of what it would have looked like in motion.

A man named Harry Truman (not the President) was living on Spirit Lake, and refused to evacuate. He claimed that he lived on the mountain, and he'd die on the mountain. He might have been able to see this at close range.