I have already posted this at Mantis, but the fact that there is no answer yet shows that my problem does not occur to anyone else, so it seems not to be code related. So this forum should be a better place.
Most Frei0r Effects give me incorrect results. The Curves give me, depending on the color channel selected, a normal picture changing into a monochrome picture that is colored with the color of the selected channel, or a white image if luma is selected as soon as I manipulate the curve in any way. No other changes of the curve change the picture now. The Bezier Curves do not change the image in any way.
The moving and scaling effect does also show a normal image until I change any parameter which makes the video disappear. Playing with the position controls shows the image sometimes, as it seems to be displaced out of the screen and the controls seem to be some kind of inverted.
Similiar problems appear with other effects, too.