You must have a sniper and scope 2 time.
https://www.youtube.com/watch?v=OsLXgMFncjI
1. Go in Escort (map: Rising Dust)
2. When you are attackers, at the end you can see this little window.
3. Take Sniper class and go near of window.
4. Scope two (2) times where the Rocket Boxe.
5. Move Left, Right and maybe you will see a black screen or something like that.
Don't tell me you don't understand, I don't care! You have a Video!