We use Dropbox and create a 'File Request' folder. Once we create this, we copy the link and share it on our social media, or newsletter/website. This allows anyone that has taken video or photos to upload them to our Dropbox folder, which we can than sort, save and use for future ideas. We have an upgraded account, Professional account, so I'm not entirely sure if this is available on a basic/free account, but it is a great feature for this very reason. You can create several 'File Request' folders for different occasions as well. No one will see the files that are uploaded except the admin for that account.