So you then understand that in order to gain mechanical advantage there has to be a pulley moving in the direction of the load within the system.Yes, the pulley attached to the vehicle is moving along with the vehicle if that is what you are asking. That doesn't change the fact that you have a 3:1 mechanical advantage in the previous picture.
I'll try another video for you but honestly, at this point I don't know how to explain this to you. if this doesn't work then please go to your local high school, tech school or college and ask to speak to one of the physics instructors.
The video posted has two pulleys and it shows a 2 to 1 mechanical advantage he even explains that the fixed pulley is only for change of Direction the pulley that give this mechanical advantage is the pulley on the load not the one that's fixed.