Movie making lends it rather neatly in SecondLife. Here is a platform where you can create sets any which way you like and then you can populate the sets with actors and actresses who can be tailored to look just as the situation demands. So the same set of human 'actors' or manipulators can work with avatars who can take on any shape and size , including fantastic ones.
The behaviour of the avatar-actors have to be defined in terms of animation scripts and this calls for signicant programming, but the best thing is that these animation scripts can be both reusable and incrementally improved. What this means is that while the first movie can have an avatar-actor who delivers a jerky slap that lands on someone's shoulder, the next version of the script can create a smooth slap that hits the intended victim right on the cheek ! And what can be done for a simple slap can of course be extended to any other action ... depending on the directors imagination.
The 3D sets are of course any set-designers delight ... not to talk of the treasurer since everything is done virtually using 3D modelling tools that can be uploaded and imported into Second Life.
Finally the photography ... the crude way of doing all this is to (a) shoot your desktop display or (b) project on the wall and shoot the image. But if you are a pro, then you can easily rig up some basic apparatus to pipe the display from one machine into another which is configured to recieve the same and convert it into an mpeg file.
As an example of what can be done, please see our movie "Are YOU Real ?"
[ this movie may initially take some time to load, and the first pass may be jerky, but if you are patient, then from the second replay onwards, it is quite smooth ]
and remember, there are no copyright issues in using Second Life as a platform since one of the cardinal principles of this world is that you own the IP of anything that you create here.
Cheers and happy movie making.