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Decide on your window size and frame rate and then encode as a QuickTime movie using the Sorenson 3 codec, its a good balance between quality and filesize.
 
Personally, I'd download OpenShiiva (check VT), and use that. It produces MP4 video files that are quicktime compatible, and with the XviD codec (which is playable in QT with the 3ivx codec) they look spectacular at very low bitrates.

If you have QT Pro, you could also just use Apple's MP4 compressor--it actually works quite well, and in my experience produces much better files than Sorenson 3, though with Cleaner you might get better results with Sorenson 3.
 
Cleaner is one of the best rendering engines around in the non-high end sector, it does produce noticably better results than QT pro, but its Slooooooowwww on anything other than a turbo-nutter-bas*ard of a G5.

Sorenson is a bit more cross compatible too, you'll need to be running QT6 to use MPG4 I think.
 
If you care about compatibility, Sorenson 3 in a .mov.

If you want quality and the best all-round result but don't care about windows users or backwards compatibility, pixlet (or MPEG4 if you don't have panther) in a .mov.
 
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