This article is from the Mac communications FAQ, by Bruce L Grubb BruceG6069@aol.com with numerous contributions by others.
Quite possibly as there have been serveral codecs for AVIs over the
years each of which have been respresented on the mac with it own
extension: Intel Raw Video (1.10.20.02), Indeo Video (3.22.24.09),
Indeo Video4 (4.4.0), and Indeo Video5 (5.0). While Windows did have
an i235 AVI codec no Mac extension exists to view these AVIs.
The mac extensions Intel Raw Video and Indeo Video codecs were
originally included in a Quicktime 1.5 and higher program called
Video For Windows (c1994) which allowed to QT view these AVIs. Today the
Indeo Video codecs 3 through 5 plugins for Quicktime 3.0 and 4.0 can be
found at <http://www.apple.com/quicktime/technologies/indeo/> and the
Intel Raw Video seems to be part of the MacOS 8.5 install.
Futher complicating matters is the emergence of a new AVI codec known
as DivX. Currently the only way to play these DivX AVIs on a Mac is
use DivX Player <http://mac.divx.st/download/index.html> with Windows
Media Player 6.3 (DivX Player does NOT work with version 7 of the
player); unfortunity the OpenDiv codec
<http://www.divx-digest.com/software/divxcodec4.html> which is usable
with Quicktime does not seem to be able to decode DivX AVIs.