First, make sure that you place the Chroma Key Color transition in between the overlapping sections of two videos.
After adding the Chroma Key Color transition, right click on it and click Transition Settings (you may also double click on the transition). Select the color that you want to make transparent. Video Edit Magic can render any primary or custom color as transparent. To select a color from the video, you can drag the mouse over the video's image and click to select the correct RGB composition. Click 'OK' to apply the changes.
The Chroma Key Color transition renders a color transparent that exactly matches the selected color's RGB composition. If the video you want to superimpose contains a lot of variations to the specified color, they will appear as remnants. You may try using "Non Red Key" and the "Invert" operation to minimize or eliminate the remnants.
Refer to the article "Applying Transitions Correctly" in Video Edit Magic's Help file for details.
You can also view this article online at:
https://www.deskshare.com/Resources/articles/vem_applying_transitions.aspx