[soruly]

Unlike movies, the content on screen recordings usually remains roughly the same for minutes before switching scene. So it can achieve significantly higher compression ratio even at high fps

[capableweb]

I wrote more about it here: https://news.ycombinator.com/item?id=32223240

But the TLDR, ffmpeg can remove duplicate frames:

    ffmpeg -i in.mkv -map 0:v -vf mpdecimate,setpts=N/FRAME_RATE/TB out.mp4