Intro
In SG, fall damages seems to be buggy. I have only tested on the NA server, however, I have reproduced the results consistently on multiple platforms and in both CS and regular games.
Explanation
Below, I have a link to a video of all the fall damage glitches that I have found. I recommend you watch the video as you read this. The first is inconsistent water fall damage. Sometimes, you will take damage even if you land in water. Other times, you will not take damage in the same circumstances. The next is lily pad fall damage. In my testing, falling on lily pads that are on water from large hight does not damage the player. The next section has to do with launchpads. Falling from a large hight and landing on a launchpad will not damage the player (you can still take fall damage whenever you land on a launchpad if you walk off of it before it pushes you upwards). Players also take no fall damage after using a launchpad, even if they have the momentum to warrant a large amount of damage (I did not include this in the video as I felt that it was a well known issue).
Version
I recreated these bugs on Windows 10 Edition as well as on Pocket Edition. The results were found to occur in 1.16.201 and 1.16.210.
Firstly, be sure to read the following post before submitting another bug report. We ask that you only report one issue per thread.
The issues with falling onto blocks near water and not taking damage have already been reported and logged.
There is an issue with players taking damage when falling onto water-logged blocks, such as the sea grass in your video, this has been logged.
As for players not taking fall damage after using a launchpad - this is intended. If you do not land directly on the launchpad, or walk off it before you get launched, you will take damage, this is also intended.
