When trying to sweep and doing it naturally, take a huge breath and than breath out so you feel your hands are relaxed, than start sweeping and control your hands - they should always be relaxed. Once you you feel relaxed you can work on correct technique.
That mp3 is a good start. Made me to remember how i started

-> same boring "turtle-speed" sweeping - so don't worry. You're on the right way!

When you get it up 20BPM - record another one, ok?