The kid at 1:24 afraid the pendulum would hit him in the face reminds of jerk instructor I once knew.
He was a physics Post-Doc when I was in grad school and he was filling in for the prof in the first year physics lecture. The demonstration was the classic conservation of energy with a pendulum: a bowling ball tethered to a line running about twenty feet to the ceiling. The instructor places the bowling ball under his chin and lets the ball go. Because of conservation of energy, when it returns the ball will only swing back to the highest point -- the same spot it started from, right under the instructors chin. However, this jerk post-doc either was remarkably arrogant or didn't understand the physics (or likely both) because after he let the ball go, he smirked and placed his hands behind his back, shifting his face forward a couple inches.
When the ball returned -- WHAM! -- two missing front teeth.