What it is: Makeup with grease/oil as a base for the pigment, instead of water.
Cost: The Halloween type makeup, which is basically colored Crisco, is very cheap. Professional greasepaint is much more expensive.
Appearance: Pro greasepaint covers well, blends well and can be set. The finished look is authentic.
Availability: At least around Halloween, the cheap kind is widely available. The more expensive stuff should be findable all year long in costuming stores (the one around here is The Costumer - check around in your area).
Application: I used the cheap, Halloween kind of grease makeup to do my first face, Mistoffelees, and I found some major difficulties in the application. The kit I used was a tricolor clown palette of white, red and black. Of course, I used only the black and white. As soon as I began to apply the white, I noticed that it didn't cover very well. It seemed to take a lot of makeup to get my face to look even remotely white, and even when I was done, the pink of my skin showed through. (This should not be the case with the real greasepaints, I was using Halloween makeup.) The thick, greasy texture of the makeup made it difficult to apply detail lines such as whiskers, lip lines, stripes and eyebrow outlines - really, do imagine colored Crisco, that's pretty much the texture. And unless you're very good, it will probably be tough get the feathery (or furry) look of some of the makeup designs. The same thick texture did help to block out my eyebrows, though, where with something thinner I might have had to use wax or spirit gum to hide them.
Durability: One of the major drawbacks in my mind with the cheap stuff is its durability. I didn't set it (since I didn't have powder), which was probably part of the problem. After a while of wearing it (I wore the Mistoffelees face for about 2 hours, not including the nearly 2 hours it took me to get it on.), I noticed that the white would gradually fade and need touching up. I don't know what happened to it, if it melted, evaporated, or soaked into my skin, but it just faded away. It's greasy and sticky, so it's a pain to get off of clothing and application items. Real greasepaint should behave more like cream, though it may take more washing to get it out of brushes, etc. Do set it, it will last much longer that way.
Appearance: It was okay. It certainly didn't give me the nice, flat, matte look of the video faces. (But again, I didn't set, and I was using the cheapo makeup.) It holds the sponge or brush marks like some kinds of paints do. (Think Van Gogh's paintings...) Because of that, it can end up having streaky or spotty coverage. If you're careful, though, you can eliminate most of it, so that from a few feet away you can't really tell. As I said before, it's difficult to do details, so your pattern may not end up looking as thin lined as what you were aiming for. Again, real greasepaint shouldn't do this.
Removal: It wasn't as difficult as I thought it might be. My recommendation for this would be to, rub some petroleum jelly ore cold cream into it, then wipe it off with tissues or paper towels. (Tissues are nicer on your face, usually, but it does take a lot of them.) After you've got it mostly wiped off (Careful around your eyes with the wiping. It can irritate them or push makeup into them if you're not. ), then wash with soap and water. I did notice that a slight film of grease (colorless, but yucky feeling) remained for a while afterward, even with several washes. That wasn't too bad, though. It probably would have come off if I'd had a better cleanser, but I didn't prepare ahead very well.
If you're doing this for Halloween trick-or-treating, the cheap stuff would be a fine option. No one will notice the texture and detail in the dim light, which will knock out two disadvantages. Also, you're not likely to need it for many hours. If you're planning on wearing the face for a party or other event, don't use the cheap stuff, it's likely to melt off after a while, and it won't hold up to close inspection. Real greasepaint works fine, similar to cream, but is much more expensive. If you're on a tight budget, you can try the cheap, Halloween stuff, but you have to be willing to put up with the difficulties.