I've been trying to upload the extra content for Movie Edit Pro Plus, and the upload speed is PAINFULLY slow. Is this normal? I have a fast internet connection, so I know that's not the problem.
No, "PAINFULLY slow"downloads from the Magix server is NOT normal. However, there can be numerous reasons why, at a specific time, such downloads can run slowly. e.g. many users accessing the server at the same time; your ISP experiencing very heavy traffic in your locality; a technical fault somewhere on the "line" between you and the server; etc., etc..
So, I think you will simply need to allow the connection to be maintained for as long as is required!
Sometimes, interrupting/pausing/temporarily stopping the download and then restarting it can improve the "speed".