Nice idea.

By the way, if you'd like a workaround to hold you over until this is (maybe) implemented in BIAB, try Open Broadcaster Software, also known as OBS. It's free and open source, and although it's intended for live-streaming your display on the internet, it's actually just as good at creating high-quality video and audio captures with really low file sizes.

I use it all the time to record stuff from Band in a Box and other notation programs so I can practice without having to open the software. I just keep a big folder full of practice video files.

The file format is .mp4 and you can specify audio and video encoding bitrate.

Here's an example of a Band in a Box capture that I made using OBS. The total file size for this video is a meager 5.9 megabytes!

I only recorded the chord view, but obviously you could use OBS to record the notation window as well.