Disable (and enable) all movies (except for the victory movie) with 2 simple batch files.
Unzip and drop both batch files into the "XCOM XCOMGame\Movies" folder.
Usually:
C:\Program Files (x86)\Steam\steamapps\common\XCom-Enemy-Unknown\XComGame\Movies

I was tired of watching the same old movies again and again so I renamed the movie files which skips the movies. I didn't notice any bad side effect but can't guarantee that there is not a problem somewhere. I that case, simply use the "enable_movies.bat" file.

I only left the victory movie file. But you can keep more movies by adding those files to the 'disable' batch file using a simple text editor.

Also, I would suggest to enable the movies before verifying your files in Steam. If they are disabled, Steam will not find them and try to re-download all of them.