Magix Movie Edit Pro 2018 - Video Level Curves Tutorial (Transparency Key Frames) https://youtu.be/mj1nG1YnSLM
Sometimes you want to mix two video tracks together or make one track visible one track for some time and gradually mix the other in and out for effect. This can be done with the fade handles but not very well. It's better to control the video levels with key frames by a curve made of nodes that you can drag to the level you want. Video Level Curves are available in Magix Movie Edit Pro and well as Video Pro X but it's a little hard to find. It's under the Chroma Key effect. I will show you have to use it and how the controls work for video levels. There is even a way to smooth the curve by changing the interrelation method
so the in-between key frames are added automatically for smoothing.
If you are looking for Audio Volume Curves I have a tutorial on that too: