Oh wow, that's seriously awesome. I did manage to reverse engineer the private screensaver `.appex` framework and make it work for Aerial 4 (I released a sample project/documentation last week here alongside v4 for those who want : https://github.com/AerialScreensaver/AppexSaverMinimal).

I also tried the same with Wallpaper appexes, the reversing seemed easy enough, but WallpaperAgent refused to load them, so I still use the classic trick of using my own window with a video player on top of the wallpaper, and below the icons.

I will have a look and check what I missed.