Does anyone really think that consumers know or care what a codec is? All I know is that sometimes when I try to watch a video file it works, and sometimes it doesn’t. When Windows Media Player tries to open a file in an unsupported format the response is to open a browser window with a list of codecs. That helps.
Admittedly, QuickTime is a bit more friendly when it fails, providing a reasonable error message. However, that doesn’t really help when you’ve got the new Star Wars trailer in AVI format and QT can’t handle it.
This is a longwinded way of saying: Download MPlayerOSX, and your AVI problems will be solved.