I have a 21.5" iMac that's just a little over a year old. I've been doing some reading about hardware acceleration and have arrived at a question. When viewing youtube video in 1080p or trying a 1080p video with quicktime, my cpu is still at 100% and sometimes more. The video seems to playback fine but I am wondering why I am hearing other people with much lower cpu results and I'm not seeing that? I've got the latest version of flash 10.1 for the streaming and according to my system profiler I have the nvidia 9400. Am I missing something or does someone have an explanation?