Zend certified PHP/Magento developer

How to make youtube-dl (yt-dlp) generate subtitles properly and not duplicate the text?

I’m using yt-dlp to download some videos, and I’ve told it to embed the subtitles. This seems to work, except it’s generating subtitles in the most horrible way by duplicating the text.

For example, if the audio says “but even that system isn’t fast enough to get you to other galaxies. Remarkably, there is a trick using proven physics” then youtube will show one half of the text, erase that and show the second half of the text, and then move on. Nothing gets duplicated.

What yt-dlp (or ffmpeg?) is doing is showing the first half of the text and the second half of the text on two separate lines, then replacing the first line with the second line and the second line becomes whatever comes next. The result is that I’m constantly reading the lines twice! It would work perfectly if it only showed one line at a time. I don’t know if there’s a name for this behavior, or if it’s intentional (some flag being set?) or a bug. How do I make it generate subtitles that are displayed on the video the same way youtube displays them?