(There's no video for WMA audio codec for Mac OS 9 yet. Please contribute to MR and add a video now!)
WMA Audio codec extension which allows QuickTime Player to play WMA files.
WMA_Audio.sit (279.89 KiB / 286.61 KB)
WMA Audio codec v3.0b3 / compressed w/ Stuffit
This is an extension. To install, drag and drop it on your System Folder and reboot.
Emulating this? It should run fine under: SheepShaver