In a nutshell, LCD projectors are generally hooked up to computers and used for displaying Powerpoint presentations and can show streaming video or anything else thats on your computer screen for that matter.

In fact I believe those that have done the "singing bust" effect (ie. Disney Haunted Mansion) are using LCD projectors to project the images onto the featureless bust/statues.

This is the route I'd like to go. I've used still projectors quite extensively in the past with my photography background but I don't find them as useful for my Halloween purposes.

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"Look Honey, they have... uhm... 'Dead People' in the backyard!"