The only real difference between what they've done and the picture/post I made here a year ago, is that they use a battery-pack to power it, and since I use the stir-plate for days-on-end when growing yeast, I'm not sure if that's something I'd want to do.
The mouldable plastic is not important, you can mount it in mostly anything, or even nothing.
I think you were referring to the plexiglass. The mouldable plastic was the stuff he heated and then moulded around the two magnets that were not on the fan. In essence he made his own stir bar. It'd be good if you wanted to make yourself different size stirbars.