Does anyone know what this is about?

First of all, just in case you didn't notice, this is a short film (30 minutes) not a feature film.

Update: I added a plot outline, plot summary, and user comment for this film. So click those links, and I'm deleting my description here.

Plays in the US on the Sundance Channel under the English title A Curtain Raiser, in French with English subtitles. Click link below for the next scheduled showing.

http://www.sundancechannel.com/films/500315217
That's part of your problem, you haven't seen enough movies. All of life's riddles are answered in the movies.