Dropbox allows you to move photos and videos between two accounts through a shared folder. When your photos moved out of the shared folder, they are not accessible from your first Dropbox account. You can either choose to leave the shared folder or keep it around just in case you ever need to exchange photos and videos between two accounts again. If you leave a shared folder, it lives in the Dropbox accounts of other members. In this case you may need to unshare the folder or remove members from Dropbox account.