Seems my poor intel gpu doesn't work well with webgl. I got really narrow z-culling, every 3d flipped text disappear behind a cute intersection triangle, but that's off topic; I didn't know prezzi, and seeing this kind of things live is refreshingly fun.
It's funny how (to me, at least) the Impress.js deck works, but the Coca-cola one doesn't. Not just a matter of duration, there's something in the animation. Maybe it's the little things like the way the Impress.js animation emphasises the word "tiny" - the transitions add meaning. Whereas the Coca-cola transitions don't seem to say anything extra.
He's saying that Prezi is amazing, but the fact that it requires flash is a negative aspect of it.