For a Motion Design Reel I would showcase everything to show range. If they are interested in only one aspect of Motion Design such as 3D animation then they can always ask for more. I think viewing reels on the web is becoming more and more common. I think it is best to give options. But I have to say, I personally prefer to look at reels online. A matter of fact, the COW will let you put an HD reel up on this very site.
Stephen Smith
Utah Video Productions
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