Adobe has finally added hardware acceleration for H.264 video content to the Mac edition of Flash Player 10.1:
The update 10.1.82.76 was announced Tuesday by Adobe product manager Thibault Imbert on his blog. The feature, code-named "Gala," had been announced several months prior, but was unavailable with the official release of Flash Player 10.1 for Mac in June. In a break from usual protocol, Adobe enabled the new feature in a security release.
Hardware acceleration in Flash Player 10.1 for Mac is available only for Mac OS X Snow Leopard and the following graphics cards: NVIDIA GeForce 9400M, GeForce 320M or GeForce GT 330M.