I have a few .AVI files that I want to play on my Macbook. But when I play them with Quicktime, it shows me a black screen and plays with only audio. No video. And yes I have installed Perian but that's not fixing this problem either. I tried using VLC but that didn't even show me a black screen. I could only listen to the audio. Do I have to install some codecs? If os please tell me step by step on how to do so. Cause I have no idea on how to manually do it.