Always happens on my mid-2007 24" 2.8GHz iMac with 4GB RAM and plenty of free HD space. Doesn't matter if I close Firefox and make sure .Mac syncing and no TM backup is occurring (boy are they a CPU drain and bad software). It is at least a few seconds before video appears all blocky and fuzzy and a few more till that clears up and I get a good picture. Happens with all types of video formats that I've tried since I got this Mac in 2007. Then again the same happens in QT Player (if immediate playback is enabled). I just wish VLC being third party would acknowledge the absurdity of this fast a Mac being unable to manage instant playback of video. Certainly Apple never will
So what I really would like is a setting to turn instant playback off. I can't see anything like that, but am I missing something?