VLC invites developers to add codecs to it library. QT might be a little shy in incorporating proprietary codecs for legal reasons. I also don’t know if Apple courts developers, QT is already pretty big.
In short you will have to find some sort of codec, plug in or not, and here is why.
This is a recycled reply, pardon if you alread have read it.
Problems in decodeing AVI files are not flaws with Quicktime, VLCD, WMP, what ever. It's a flaw with the AVI format, or at least it's implementation by thoes that encode the media. The frustration is that this MS format can be just about any kind of media file, and thoes that use the format don't always think about their audence, or where to point people to get the plug-ins.
Some AVI files have special "characteristics" and are designed to work with special pay or advertising services. Some of these codecs are not available for general use- both encodeing and decodeing.
Below will explain why there is no universal encoder or decoder for AVI files.
AVI = Audio Video Interleave file format, it's really an envelope for stuffing audio and video in together. As far as I know, no other standards* are included with the format. The codecs needed to decode the AVI file, are actually the important part of the media player, and normal are some sort of plug-in. Technically, any audio/video file could be made AVI, and it should be easy to turn any AVI file into its native format by decompressing* the file and by removing the header and footer. In the header it states that it is an AVI file with a string of hex, then in it states the decompression routine/codec needed, then information needed by the decoder, and then the rest of the media data should follow.
There is also no guarantee as to the content of the file that is it could contain a text file, an exe, or something other than audio and video information. Hey, it’s already told the computer that it is a media file, so what’s to worry. So a tricky little person could design a codec...better yet a codec and a special player. This player uses the codec to play the AVI files and display advertising, guarantee your age, or delete the file afterwards- what ever. This could be good for both you and the company. They could even send statistics back to some company that could better target you, though the email your provided – adware. Or worse yet, they could build up trust with anybody using the codec and player, and then one day, it gets a movie that contains a bit of malicious code that the player executes while a person watches some interesting content.
All of this aside, the AVI idea is really noble. It allows technology and compression technologies to move forward and it allows information about how to decode (and to get the decoder) the file to be included in the media. It allows enterprising programmers to utilize the format as part of a content delivery system that can incorporate DRM or features to insure its content is what the creator intended. It also allows irritating little nits to use social engineering in conjunction with software to screw with people’s information and data.
Trust me, at some point, this kind of trick will affect OSX users in mass. For now, this kind of social and software engineering is targeted at Windows users.
(*I don’t think it provides for any compression needs)
Note: I'm lazy I wrote most of the above on this thread and reposted it here today. Rant over, I'm getting back to work.