When you're falling, you can remove a slime block you are falling onto and take the fall damage as well as bounce up.
It seems that you may need to download the video to watch it. When I click on it, it doesn't display the video. I'm sorry about that.
What do you mean "remove the slime block"? Also, please make sure to only test this in Singleplayer, we do not support the Spigot software here.