Auto-Fill is a way to quickly fill your days and get a jump start on your calendar. Simply scroll to days with a camera icon on them and press the "Auto-Fill" button at the top right corner of the screen.
You can then decide whether to use videos on iCloud or not. Keep in mind, 1SE will need to download these files to use them.
FYI: You'll be able to view your seconds before deciding if you want to keep them. You can always cancel out at any time.