thanks for all the feedback! Even if there are several opinions, ill surely take the recommendation about my posture(more forward) into practice.
Yeah, i exactly have the same feeling that im not generating that much spin. Can you explain how changing my elbow angles could help here?
Why yes I can! And I'll continue on what was said above about brushing.
Brought down to the essence, to generate spin, you DON'T want to hit the ball.
...what? Yeah. Do not hit the ball. This is table tennis, not baseball. You want to be aiming not for a direct impact, but for optimal use of the
rubber to generate the ball's speed and spin.
To imagine this, you can use your hands. Your playing hand is the rubber, your off-hand is the ball.
Clap your playing hand to the ball-hand, like you would normally clap. You feel the force is directed in line with the stroke, the impact goes through the ball hand. You feel pretty much zero friction on your "ball" so the amount of spin generated is nearly nothing.
Next, angle your playing hand 45 degrees like you want to play a topspin stroke. Angle the ball hand too so you can feel the result. Keep the direction of your stroke the same.
You will feel some pull, some friction, on the ball hand at impact. Not loads, but it's clearly there. This is where I imagine your video's spin generation to be at: you do the angle, but the impact is still direct, you hit the ball.
Third, keep that angle at 45 degrees but change your stroke. Play around with it, but you're looking for the stroke where you feel serious friction on the ball hand. The sense of direct impact needs to be in the background. You'll find you need a bit more of an upward motion, somewhere in the middle between that direct impact and having no impact at all.
With that little theoretical exercise out of the way, moving on to the
elbow:
To maximize the potential for friction, and thus spin, you want to contact the ball with as much racket speed as possible. One part of this kinetic chain is the whippy motion you make when you contract your elbow while moving your arm. You don't have to overdo this, just start your motion with a little straighter arm and end it a little bit more bent. Take small steps in this process if this feels completely weird, new or unknown to you.
Other parts of this chain include body movement and wrist motion, but your "stiff" elbow stood out to me. In general, it's good practice to learn to play loose, relaxed, in order to maximize the amount of whip you can generate with only little bits of energy. Not only for efficiency, but in fact to generate maximum spin. Only on the point of contact do you tighten up the grip, so you can transfer that energy to the ball.