To do this have theater mode enabled.
1. Go into the speed infection lobby
2. Go into the multiplayer main menu
3. Go into Vault then theater find the video of the infection.
4. After watching/ending it you have it!
To do this have theater mode enabled.
1. Go into the speed infection lobby
2. Go into the multiplayer main menu
3. Go into Vault then theater find the video of the infection.
4. After watching/ending it you have it!

thanks to tehlazor for showing me this:
http://youtube.com/user/tehlazor