"Racket angle more closed, Hitting the ball more on its the upper side, Squeeze my hand tight right before hitting the ball to not release too much power."The players from those videos are almost exclusively using chinese rubbers.
The technique is mostly the same, but racket angle and contact on the ball is not the same and should be done slightly differently with equipment like yours. ( G-1 and Rakza 7 ).
My setup is simlar to yours, except I have G-1 on BH and chinese rubber on forehand ( Rxton 9 = R9 ).
Looping the same incoming ball with G-1 and the R9 is quite different.
With G-1, I need to be more careful to not overshoot the table or create an arc thats too high.
Racket angle more closed, Hitting the ball more on its the upper side, Squeeze my hand tight right before hitting the ball to not release too much power.
With R9, I can do pretty much the same movement as the guy in the video.
Angle more open, hitting the ball more on its back, loose and relaxed motion and go allmost all out.
For training technique, even if it might seem slow at the start, the most effective and in also efficient way is to train 1 aspect intensely at a time.
Meaning that for the next 2-3 sessions, you only focus on 1 single part of your technique exclusively and let the rest be as it is.
It could be forehand upper body movement, and the next session footwork and steps.
Find exercises, multiball and simple exercises like serve -> return to specific spot -> loop -> blocks/random play.
These should target that specific aspect and allow you to switch between consciously trying to achieve it and subconsciouly making it a habit, because thats essentially what we are trying to do, create subconscious habits and automatic sequences out of a conscious effort and an idea.
Start slowly and make the movement conscious at the start with a correct form and then gradually make it more challenging.
What I keep in mind for this is essentially this:
"Repeat and do it so often and so well, until you can do it bored".
It takes some time, but it will definitely pay off and allow you to effectively increase your technique over a longer time span.
Hope it helps.
If you have more questions about how to really get better at learning and improving techniques and skills overall, just ask.
This topic was really a big struggle for me and after spending a lot of time researching ,thinking, contemplating and figuring stuff out, I have gotten to a point where I can teach and coach myself and others at my club quite well.
Thats what I have been doing (blue screenshot of @jk1980) . My plan is use my hip rotation and just experiment with the stroke till I find the "right" stroke to get the most power in a controlled way. Because right now even If I hit "hard" it feels like hit or miss for me.