Turning your own videos into macOS Tahoe dynamic wallpapers is actually a rather quiet little process.

The folder path is
~/Library/Application Support/com.apple.wallpaper/aerials/videos/

Inside there are usually just one or two .mov files, like
4C108785-A7BA-422E-9C79-B0129F1D5550.mov (the kind that’s around 445MB).

The steps go like this:

  1. First go to “System Settings > Wallpaper” and download a Tahoe Aerial dynamic wallpaper so the folder has something in it.
  2. Back up the original .mov file somewhere else (very important).
  3. If your video is webm, convert it to mov with ffmpeg (visually near-lossless):
ffmpeg -i input.webm -c:v libx264 -crf 18 -preset slow -pix_fmt yuv420p -c:a aac -b:a 192k output.mov

Or the more “Apple-flavored” ProRes:

ffmpeg -i input.webm -c:v prores_ks -profile:v 3 -c:a pcm_s16le output.mov
  1. Rename the converted file to exactly the same name as the original (e.g. 4C108785-… .mov).
  2. Replace it in.
  3. Go back to wallpaper settings and pick the Aerial you replaced — you should see your video moving on the lock screen and occasionally on the desktop.

The desktop usually only plays a short segment (to save power), and it moves again when you unlock or switch spaces. The lock screen loops more fully.
If you get a black screen, check whether the exported mov plays properly in QuickTime. H.264 + AAC is the most reliable.
Take your time, no rush… if you break something, just restore the backup.
The feeling of tweaking wallpapers late at night is actually quite gentle, like giving your screen a breath of your own.

This is the wallpaper I use~