Is there a way to record my handwriting and/or drawing as a transparent video in motion? I would prefer to achieve this with my iPad, but I also have an iMac if necessary.

What I want is to record my own handwriting and put the resulting video in real time on top of another video. An app called Video Brush does this (by writing directly on the video), but the footage it exports is unusable due to being jumpy, like it had export issues. Another app called Write-on Video gets close, but the writing just appears. It doesn’t show the writing in motion.

There are a few apps that allow me to achieve this on a white background (VideoScribe, Adobe Sketch recording the screen, etc..)

TLDR; is there any way for me to either write directly on a video and make that writing part of the video or to write/draw on video with a transparent background?
I found a solution, beit a bit ineligant. I screen-record myself drawing in white on a green background using Adobe Sketch. Then use Filmaker Pro’s green screen feature to put in a different background.

Still let me know if you guys have any other ideas.