play avi movie

"Without 3rd party"?

Not going to happen.

There is no native support for .avi files on MacOS, therefore you will need some 3rd party software to play the files.

VLC from https://www.videolan.org/ is one of the better-known (and free) applications that can play AVI files.

Hello greghey1,

Thank you for using Apple Support Communities. Not all video formates are fully supported on Mac or QuickTime. If a specific media file doesn't want to open, you can review this resource on steps you can try: If a media file doesn't open or play on your Mac, iPhone, or iPad - Apple Support

This resource does explain to make sure your Mac is fully updated. If you're already fully updated, the resource suggests the following:

After updating, if you still don't have an app that supports the media format used by the file, search the internet or App Store for an app that does. You can search by the name of the format, or by the filename extension, which is the letters shown at the end of the file's name, such as .avi, .wmv, or .mkv.

You'll most likely need to convert that .avi file to a compatible version or use a different media player that supports that specific file.

Thank you for using Apple Support Communities. Best of luck.