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What you need to do is download a plugin for your quicktime program. On the page below, please download and then install the Perian plugin, which should allow you to play avi files.http://www.iskysoft.com/topic-snow-leopard/how-to-play-avi-with-quicktime-on-mac.html
Once downloaded and installed., you will then be able to play avi files through your quicktime player..
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