- Upload to Dropbox (or Google Drive, or OneDrive, or Box) using the desktop software.
- Add the video to your Vimeo account directly without re-uploading.
- Convert the Vimeo video to a native Facebook video without re-uploading. (This feature is only available to Vimeo Plus, Pro and Business customers, and is called publishing to social.)
Dropbox provides a application for your desktop that uploads large files very well. Not only can it resume interrupted downloads, but it also knows how to avoid re-uploading parts of files that haven't changed, even if the rest of the file has changed. It is far superior to the upload system you find in browsers and on websites like Facebook. Google Drive also has a desktop application, and I assume OneDrive and Box do as well.
Now that you've uploaded the file to the cloud, how do you get the video added on Facebook? Unfortunately, Facebook does not have a feature that lets you add videos directly from Dropbox. But Vimeo does. And Vimeo also lets you publish a video from Vimeo directly to Facebook. Not that the resulting Facebook video is a real native Facebook video, it is not a link to Vimeo. This publishing to social feature is only available to Vimeo Plus, Pro and Business users.
So all you need to do is convert the video hosted on Dropbox to a video hosted on Vimeo, and then convert it to a video hosted on Facebook, all without re-uploading.
Note that although you don't need to re-upload the video file, this process does take time, as Vimeo has to process the video before allowing you to publish it to social. Obviously, this whole process is a workaround the fact that Facebook doesn't provide good tools to publish large video files.