Imagine the top part as A and bottom part as B
Now there is tension between both the points and when he let goes of point A,both point A and B rushes towards the midpoint of A and B but point B seems stationary because it is affected by both tension and gravity (which has the same value in this case) which cancels each other out.
It's because no one has told the end that they're falling so it thinks they're still hanging.
Basically slinkies only act like they're affected by gravity. When viewed in slow motion, it becomes clear that their acting isn't as flawless as they think it is.
On the moon, with 1/6 Earth's gravity, the bottom part of the slinky wouldn't be pulled as far away from the top part, but when released, the top part would fall slower towards the bottom, so it would still take the same 0.3 seconds that it does on Earth to fully compress. That 0.3 second compression time would also occur on a higher gravity planet-spring stretches further, but faster drop of the top section because of the increased gravity.
Now there is tension between both the points and when he let goes of point A,both point A and B rushes towards the midpoint of A and B but point B seems stationary because it is affected by both tension and gravity (which has the same value in this case) which cancels each other out.
Top part is also pulling on bottom part, causing it to fall slower
Gravity only propagates at the speed of sound in a material.
Basically slinkies only act like they're affected by gravity. When viewed in slow motion, it becomes clear that their acting isn't as flawless as they think it is.