If it is saying that you are missing the main_menu.webm or something like thatDuring that intro clip there are three different error messages. I can rollbacl, ignore, console and so on.. Clicking three times ignore throws me back to main menu and that's it. Every time same place. After introducing gym girl and maybe one more after that. Error, error, error and main menu.
You need to go into game/images/animations/gui
you will see a default_main_menu.mp4 file, create a copy of this file and name it main_menu.webm which would change the file extension from mp4 to webm
This is what I did when I got the error that I think you are getting and it resolved it so I can play the game