Hi, it should not flicker,
However, remember Video Gogh has to render frames in order (e.g. won’t work to distribute it on a render farm), and if you set something at other then first frame, you have to go to first frame and purge the memory (or change the “Regenerate Brush” button state, so AE cache gets cleared as a parameter changed)
If you have more issues, you can always send a project to techsupport@revisionfx.com