I am attempting to open video from my Flip camera and am only getting audio with no vide.
The AVI file type mere indicates that the frames of audio and video compressed data are interleved within the container to maintain A/V synchronization. Since the AVI container is not limited to any particular combination of audio and video data compression, it would appear the audio compression is supported by your player but the video is not. AVI is an older file type normally associated with "legacy" codecs which are, by default turned off under Lion and Mountain Lion operating systems. E.g., many Casio digital cameras store video clips as Motion JPEG video with WAV (PCM) audio in an AVI container. Since the Motion JPEG was disabled with the introduction of Lion and, unless you re-enable it, remains disabled in Mountailn Lion, such files would not play the video data but would the audio since WAV audio remains supported. In this case, you would either have to enable the codec using the Terminal app in your "Utilities" folder.
Therefore, your first requirement here is to learn what codec was used to encode the video content in your problem file. (See "Format:" entrin in your QT Player "Inspector" window.) Once you know which codec was used to create the file you can then decide what further action to take. For instance:
1) If the codec is a "legacy" codec that can be re-enabled, you would re-enable it.
2) If the codec is one not currently supported by your system's codec component configuration, you check to see if the codec is available through a third-party such as the "Perian" codec package.
3) If the codec is not supported by QT and not available for the Mac as an "add-on" codec, then you might have to play the file in a third-party media player that provides its own codec support.