Hi Jesse,
I think the first thing you should be asking is why do they want an AVI. Is this just for previewing the work, or will it be the final delivery format?
AVI is just a wrapper, like a QT MOV file, and there are a number of different codecs you can use, just like with Quicktime. A lot of the standard ones date back to the dark days of video encoding and are ropey at best. For a preview movie this might be acceptable. For final output the only one to use would be Uncompressed, which would result in a very large file. For 10 minutes, that would be way bigger than DVD-R could handle.
The best thing is to ask what will happen with that file after you give it to you client, so that a proper workflow can be figured out.
HTH
Ben
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