Unfortunately, AVI is not sufficient information. There were literally hundreds of codecs for the AVI wrapper and only a few, less than a dozen, were ever available for the Macintosh. It’s a deadend convention, not even Microsoft actively support it anymore. What you want to do is insist your clients abandon their old fashioned ways and gracefully enter the 21st Century already. Convert their ancient files or replace their ancient applications with modern tools.
It’s rather like saying, “I have an IMAX editing system but my client has some Super8 they want me to assemble. It’s just film, right? Should work, right?”
bogiesan
This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”