That's because of the main menu "animation". It's very poorly coded and will break the game if your system isn't top of the line.
Here's a method to fix it:
- Extract the scripts with rpatool or one of the tools of the forum
- Remove \Milfy_City-0.6e-pc\game\script.rpyc (or move it somewhere else as backup, just don't leave it in the game folder because ren'py will actually still try to read it). This is the bytecode version of script.rpy
- Drop the script.rpy I attached here in the \Milfy_City-0.6e-pc\game\ folder
Basically what I've done is change line 29 of that script from the bad webm to a random game image.