I've been using video projectors in my cemetery scene for several years now, and I've compiled some practical tips for incorporating them into your haunt as well.
And if you specifically want to make an animated jack or jane o'lantern, check out Jack, the animation software I wrote specifically for creating pumpkin faces.
At a NorCal Haunters Group meeting, we held a projector “bake off” to compare various projectors people are using in their haunts. See the results.
Personally, I'm a big fan of LED pico projectors for haunting. They have built-in media players, quiet fans, and are so small you can hide them inside all sorts of props.