Slinky, anyone?

Saw this on Crazy Russian Hacker’s Slo Mo Lab. I love CRH. Comments said they stole it from SloMoGuys, checked them out, too. I put CRH first, cause the other one kind of gives it away in the intro. But, if you expand the comments after PredatorRex10 on the second one, it explains the science. Science is so cool.