Open your Windows Explorer and jump to your CoD5 directory: navigate to -> main -> video. There you will find a file "Treyarch[.load]" or [.bik], not sure. There is only one file with this name Rename it to "Treyarch.bak" (preferred solution)
This file is the intro video, renaming it should solve your issue. you can also try renaming the video folder to video1 or "fck_treyarch". If you do this, it may be possible that you will have to run the game in safe mode. I'd prefer the 1st method