The movie plays smoothly when VCR is connected directly to a TV. (no converter inline)
The problem occurs when using the VHS to digital converter with Poweredirector 12
Checked:
25fps PAL,
4x3
Hardware accelerator off. (and on)
The scene is outdoors, so no strobing sources.
The same flickering occurs with OBS software too!
In both software the resulting mp4's the flickering is recorded.