We are an intermediary between various web technologies that don't play nice together. Mover takes your files from one place and copies them to another. No downloads and nothing to watch over - our web-hosted app does all the work!
When we transfer files, we are downloading a copy to an ephemeral (temporary) server and uploading it to the destination. Upon successful upload, the file is removed from that server. We aren't performing any actions beyond copying your files and folders (and sharing permissions, when applicable), which means there's no risk of deletion!
Here is an example of what Mover does and how it does it: Example Migration - Box to Google Drive