I'm planning to build a visual interface that would allow users to preview individual scenes. Meanwhile, if the main video build is too long because you have lots of scenes and want to check out how one would look with different parameters, just create a different script file with that scene only and build it. that's the beauty of text file editing, you can easily copy and paste and experiment.
I'll give it a try, perhaps its so fast that previews aren't really necessary.
I also think this could be an amazing tool for personalizing video marketing too