It's possible that photos/videos shared just between Album Admins might end up in your 1s Movies. However, 1s Movies are only delivered to the Album Admins in an album.
To add a 1s Movie to your album, go to the Collections screen and tap "Share in FamilyAlbum" below the 1s Movie you'd like to add. You'll then have the choice between sharing with everyone in your album ("Share with Family") or just other Album Admins ("Admins Only").