iChatSniff is a cocoa software that plays iChat audio sessions by reading pcap-formatted packet dumps. However, the iChat video feature remains untested and may yield erratic outcomes. iChat AV is mandatory for installation.
It's important to note that while iChatSniff is an excellent tool for playing back audio sessions, it hasn't been tested with iChat video. As a result, it's difficult to predict whether the software will work well with iChat video or not.
In terms of system requirements, iChat AV is the only thing you'll need to use iChatSniff. If you have a Mac with iChat AV installed, you're good to go. And once you start using iChatSniff, you'll realize just how easy it is to use and how useful it can be for anyone who frequently uses iChat audio sessions.