There are two options for uploading videos to Vimeo- free and paid. I have accidentally uploaded videos to the free option more than once. After waiting hours for the large files to upload, I discover that I have once again done it the wrong way. Then I have to delete and re-upload.
First off, you need to have a Pro account to sell videos. Once you have signed up, and set up payment, go to the Manage Videos drop down menu and Sell Videos. The steps are pretty straight-forward from there.
Do not upload your video under the blue, top right-hand corner New Video link. These will NOT let you add sales and are the equivalent of uploading a free youtube video. If it is private and for sale, this is the wrong place to do it.