Hi.
There have been over 4 gameplay videos. Unfortunately, 1 has the same issue you have, it isn't a freeze screen, there is supposed to be a text on it, I don't really know why it occurs, because the 3 videos didn't have it.
If you have that screen just press RMB and it will bring you to the main screen. This is just a demo, which means the application isn't stable, so not really a bug or surprise.