Feature request - Make it compatible with already downloaded Apple Screensavers

#### Required information
In order to help us sort your issue, we ask that you provide the following information:
- [ ] Mac model: MacBook Pro 14" 2021
- [ ] macOS version: Sequoia Dev Beta 3
- [ ] Monitor setup: Only MacBook Screen

Feature request -
I have already downloaded many video from Wallpapers section in macOS settings (Landscape, Cityscape, Underwater and Earth). I do not want to download same videos again taking space. Please use the already downloaded videos.

No source files, tests, or entry points are identified in the issue, so first locate the code that discovers and downloads Aerial videos. Determine how the videos already downloaded by macOS are exposed, then verify that Aerial can use them without downloading duplicates.

Written by the indexing model from the issue text.