This is from Lucas Arts… I forget where I got it from. Hope it helps.
WHAT DO WE WANT TO SEE IN A DEMO REEL?
Animation
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Show weight, balance, timing. Basic motions like lifting, sawing, pulling,
pushing, and interacting with scene elements as opposed to simply running,
jumping, or walking.
Modeling
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Reality is the key here. If it is a human it should look like a human. Show
a sense of proportion and detail unless youre going for a stylized cartoon
look.
Lighting
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Should create a mood or atmosphere. Dont have over-lit scenes just to show
off your models.
Camera
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Have an effective transition without leaving the viewer in a state of vertigo.
Have a nice flow between shots to help the viewer understand what is going on.
General
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Show your best work only. Show your best work first. Demo reels should not be
longer than 5 minutes.
Show each work once. No need to repeat the same piece.
Use good judgment on music or audio that accompanies the work. Didnt someone
say, The audience is listening?
Spend the time to do at least one thing really, really well. Everyone has a
walk cycle - how do you make your reel stand out? Model an object with high
precision and high quality texture maps.
Work on lighting. This seems to be the most overlooked thing on a demo. Show
how lighting adds mood or excitement to a scene or how it can be used to
increase efficiency by reducing the number of elements that need to be built
in a scene.
Use good textures. Are your textures appropriate for the model, or are they
just the ones that come with the software? Show that you can create your own
textures and have good judgment on how to use them. Do they add detail that
otherwise would have to have been modeled?
Show wire frames of models. Wire frames show whether you hacked the model
together or built true shapes and forms. They also show how efficient you
are as a modeler.
Show low-poly work if you want to get into games. Hi-res work is glamorous,
but most games are low, low poly work.
Have high quality (dye-sub) prints made of your work. Low res ntsc video
wont do justice to your environments.
Fix any technical problems. Dont have any dropped frames or animation
spikes in your work.