Do I have to manually lock a folder after viewing?

In your overview video I noticed it shows the user seemingly being required to re-lock a folder after accessing it. This seems like it would be pretty annoying. Also, it also implies that forgetting to lock a folder after being done with it would leave it unlocked and therefore defeat the benefit of having this encryption software.
Am I misunderstanding that part of the video? What happens if somebody accesses a folder, does not re-lock it, and then has their laptop stolen? Would the data be secure or not?
Am I misunderstanding that part of the video? What happens if somebody accesses a folder, does not re-lock it, and then has their laptop stolen? Would the data be secure or not?