You can put a Mute automation on each video track this will allow the one below to show.
So each track was duplicated and the volume turned right down on it.
The "Change selected realtrack source file type.lua" is run on each selected video track using mp4 input.
View > Video will show video window.
You can render to new video.
You can get Biab to render the chord sheet to video and use that with a picture in picture video FX.

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