Challenge accepted? Here's what this HTML5 'ad' looked like to me in Chrome, implemented in 20 minutes in Flash.
I have no idea is this is 'more power efficient' (what does that mean?), but it takes ~2* the cpu (~20%) but 1/2 the memory (~95mb) of the HTML5 version in Safari on my mac. Interestingly, it takes just ~5% CPU on the same computer in Windows, so perhaps Steve needs to stop moaning and fix up his OS support for Flash instead?

Yes, I know the spinny 3d box thing is 'wrong', but the point is it doesn't work in Chrome, what I implemented here was what I saw in Chrome.
The Flash will look the same in all browsers,
wonder if your clients will accept that their HTML5 ad may only work in ~6% of browsers?