Ueyama-san, the programmer who made those 3D demos, is the same programmer who did those Gecko reflow videos (Japanese) that were widely blogged about and discussed at Doug Turner’s blog: What is a reflow?
EDIT: Unfortunately those reflow videos are no longer available at Google Video (grrr). I’ll see if Ueyama-san can upload them to a different video hosting site.
EDIT 2: Gecko reflow videos have been moved to Youtube thanks to Ueyama-san!
Gecko Reflow Visualization – google.co.jp
Gecko Reflow Visualization – mozilla.org
Gecko Reflow Visualization – Wikipedia