I'm stuck at the pick pocket lock even after taking the hints it's confusing. What to do i can't even..

My game was stuck at this part I had to exit an reopen the game again. Anyway, you need to press the metal thingy every time the the lock vibrates that's it. The little bars that go up and down vibrate at a certain point, that is when you should press the metal thingy I don't know it's name ( ≧∀≦)ノ.