Feedback on RPB form?

I think you arn't getting on top of the ball enough, especially on the first few, you got a bit better after a few shots.

In general, I think this is a symptom of a lack of confidence in the shot.

You seem to be brushing too much upwards from behind the ball, rather than fowards from on top of the ball. This tends to be the shot when you want to control the amount of power on a shot, because you arn't confident of forcing an arc onto the shot. When you hit from behind the ball, you can make a lower energy shot, and just have the ball drop with gravity. The problem is, when you want to play the same shot, but harder, it will go long, because you are "hitting" the ball too much and not brushing enough.

In reality, you want to brush somewhat more on top of the ball, and play a higher energy stroke. Then trust the topspin to create the arc. This is a much more scaleable shot when you want to add more power.

If you watch the close up shot in the introduction of the Wang Hao video, you see that the trajectory of his bat during the shot, is almost entirely horizontal. With these balls that you are contacting quite high above the table, and not backspinning, that is a more appropriate stroke, whereas the stroke you are playing is more suitable to lift heavy backspin (if you played the stroke harder).

If you are forcing your arm to go forward, maybe move closer to the ball so your arm is more natural.
Try to use more of your wrist, instead of the whole arm moving upward, because the ball coming at your is topspin.

It seems like the ball hits the edge of your racket quite often, I would suggest don't close the angle of the racket so much, and also watch where the ball goes so the ball hits the centre of the rubber.
I hold the racket differently, with my fingers curled up so there is more room on the back, i.e. more room for error.

I'm sure you will get the hang of it soon! Robots are good for basic strokes.

To me it looks mostly like you just keep practicing. You are at a decent starting place.

You look very stiff. Relax.
Try to use a whole body instead of (almost) arm only. Bend knees a little more before the shot and extend them (not necessarily full extension, keep knees slightly bent) while making the shot.

The rotation of the body with RPB is non-existent or very slight due to the nature of the shot. it comes up from the bottom. Forehand shot on the other hand comes up from behind in circular motion hence the body rotation. the power from RPB comes from aggressively extending the body from lower position (and of course proper arm movement).
Trying to rotate significantly body with RPB would cause you to loose a lot of speed for very little (or even nothing) to gain. The only situation would that it could make sense is the smash when you have enough time to prepare for that kind of shot and don't expect the ball to come back as the recovery will be slower.

Interesting match with a lot of nice usage of RPB is https://www.youtube.com/watch?v=X8i2bncy4qo