"people show their true colours in life threatening situations" no, they show you what they act like when they're mortally terrified, an emotion notorious for literally turning your entire brain off to the point where people who go into those situations as a profession need to be literally trained on how to not have that happen
These solar eclipse shadows form due to the distance between the sun and the leaves on the trees. The distance and the proximity of the leaves to one another cause for a "lensing" type effect, making the eclipse shadow clearer to the human eye.