Thank you all for the compliments !
This is what I built for to hold the scene and the camcorder;
The platform is mounted on a big bearing and can rotate, this is where I put the setting.
The camcorder is mounted on a mechanism of arms which allow movements about two different axes of rotation, so some variety of movements are possible.
There are two white large counterweights which can be moved to balance exactly the mechanism about the main axis of rotation, which allow for the vertical movements of the camcorder
Then there is a littler movable counterweight, (above at the right in the photo below), which is for to balance the weights about the secondary, horizontal axis of rotation, which allows for the tilting of the camcorder.
So the tilting is independent from the vertical movements of the cam.
The movements are all on bearings and when everything is well balanced, even just blowing is sufficient to move the cam slowly and very smoothly.
I added some thin arms which are levers which link the two rotations together in some different ways;
depending on the way these arms are linked, I can move the cam up and down keeping it always horizontal, or, I can make it tilt so that it stays always pointed towards the same spot in the setting, or intermediate movements are possible.
With one hand I rotate the platform, with the other one I control the vertical movements of the cam, and the levers control automatically the tilt of the cam.