That Gonz clip is awesome!
To pause on any of those and see his upper body already turning before the front foot is decked is the key to doing them on bigger ramps.
As said, smaller tighter transition and bigger ramps with a steep if not vertical face are the best to do them on, but learning them on something more mellow is good too and the best way to work up to something bigger or steeper.
The funny thing is the trick will come more naturally when you don't try to force it, but starting with the quick "tap and turn" is the best way, then get them up a bit more and a bit more, best when you just have the same amount of speed if you were going to kickturn just under the coping or lip, not so much that you would end up on top like a 50-50 or other grind. If you turn the board slightly the opposite way to the way you are going to turn in, it gives a much better pivot point than just straight as well, which is important to note.
To slide them, come up on an angle and stay low and almost do a quick little motion to get the board straight over the coping with weight on your heels, the way you would turn onto a low curb or something, but you have to stay closer to the middle of the board on the coping or lip if you are on smaller or more mellow edges, depending on how much wheel clearance you have on the face of the ramp and platform. Again tighter or steeper ramps will have a lot more clearance, so you can have the board way more decked to slide than on something smaller or more mellow.
Keeping weight over the back foot is key, with the front foot pushing down for a second once you get the board over the coping without you trying to push the whole board up as that will just happen. Same with the back foot or ankle curling motion, which is not so much the foot or ankle rolling, more just your body keeping the leg straight when your body is out behind your board, weight right in the ramp.
It is one of my favourite tricks from the 80s when I first learned them, but it took a while to get them on bigger ramps with a quick enough turn to not slide half way down the ramp back then.
If you don't get your upper body to turn enough or stay low enough over the board, they will be hard to get back around well, or leave you off balance or slip out more often, but finding something comfortable to learn them on will definitely help a whole lot.
Sorry if I am going on, but this is pretty cool too:
https://www.instagram.com/rockandrollclub/https://www.instagram.com/p/B-cnrsklqaf/And Lance Mountain sliding one:
https://www.instagram.com/p/BX3LvMWhxrb/