Adobe recently updated Flash Player 10.1 for the Mac which finally enables hardware acceleration for H.264 video content.
You should notice now a nice difference when playing H.264 content on your Mac in terms of CPU usage. We rarely enable new features in security releases but we really wanted to enable such a cool feature.
Note, if you wanna make use of the feature, you have to be running OS X 10.6.3 and have one of these video cards: NVIDIA GeForce 9400M, GeForce 320M, or GeForce GT 330M GPUs. And below is a list of computers that support the feature: