I want to automatically back photos and videos from photobooth to google photos, but don't know where they are stored.
The PhotoBooth Library is within the Pictures folder of your Home Folder.
Regarding automatic backup, there is no direct way to do it as Photo Booth does not have many options for that. You can try following:
Get Desktop Uploader app for Google Photos. Alternative way to get it is by opening the sidebar on Google Photos in your browser and clicking App downloads.
After installing the app and logging into your Google account, you can select which folders Google Photos will automatically back up. So try to add this path to auto backup:
"/Users/your_username/Pictures/Photo Booth Library/Pictures"
You can right-click "Photo Booth Library", and select "Show Package Contents" to see the Pictures folder, or open directly from Terminal with:
open ~/Pictures/Photo\ Booth\ Library/Pictures
they are stored in Photo-Booth Application
you can create/use following command to create a symbolic link, to link photo-booth-pics directory under your Pictures directory
ln -s ~/Pictures/Photo\ Booth\ Library/Pictures ~/Pictures/photo-booth-pics
After above command Go to /Users/your_user_name/Pictures/photo-booth-pics/ to see your pics