Try installing the K Lite Codec Pack.
Alternate Video Branch
You can also try a version of the game where the videos are saved in a different format.
This can help when videos are not playing, or freezing on your system.
- Right-click on Not For Broadcast in your Steam library and click 'Properties'
- Select the 'Betas' tab
- Under the drop-down menu select alternatevideo
- Once the game is updated it will be ready to launch!
Download and Install Windows Media Feature Pack
Download Windows Media Feature Pack Here
Some Windows installations don't include the Media Feature pack which includes the codecs you'll need to see the videos properly. So make sure you have that installed too.