or go with the pro's, turn the background to green and use the greenscreen functions of the video editor.

or turn the preview to silhouette (Ctrl+1) and render an avi in Preview instead of using FireFly, this will generate a stream of masking frames (After Effects deals with that). set background to black for max contrast.

Hope this helps.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though