I installed perian a year ago on os x leopard and never had a problem watching any videos on quicktime. I upgraded to snow leopard, installed perian again (and flip4mac and divx codecs) and now the avi files i have no longer work. Apples website says it should but it does not. I havent upgraded my macbook yet so i put the avi file on a usb stick and tried it on my macbook running os x leopard and it ran fine. The only avi file i got to work was one that was converted (originally a .mov file). Anyone managed to get avi's to work on quicktime x?