I'm not sure whether you'll really care to know, but that video wasn't made from an MRI scan. If you're currently eating and/or are squeamish, you may not wish to continue reading. You have been warned!
A donated cadaver was frozen in ice/gelatin, then images were taken. Between each image, a 1mm slice was removed from the ice. All those blue flashes are, I believe, cracks and other things in the ice.
It's called the
Visible Human project.
I'd guess the problem with your script is that, each time, it's looping from frame 0 to (current_frame). I may have an experimental plugin that can greatly improve this.