Movies... of the FUTURE!
We're so used to the idea of movies as a form of popular entertainment that we often forget that there was a time when people were still trying to figure out what the heck moving pictures are good for.
Take this set of predictions regarding Hollywood's future from Hugo Gernsback. I'll bet Cecil B. de Mille never thought of using film to teach dancing on a glass floor.
Maybe the tap shoes' problem had something to do with it.