Hulu (run by NBC) tested HTML5 vs. Flash 10.1, and they said HTML5 is great, but it just doesn't work for the content that they stream. Not only that it is very insecure when it comes to streaming the content. There was also a study between HTML5 and Flash 10.1 on both Mac and Windows OS's. Flash 10.1 performed just as well, if not better, than HTML5. Problem for the Mac/Safari combo was at the time, Apple wouldn't allow Adobe access to the API needed for hardware acceleration. I have not heard how much improvement there has been since Apple gave limited access.
Still I am glad some giants are sticking up to Apple's communism. Job's claims that Apple is an "open platform," when in fact it is the most closed platform out there.