The dough is placed on moving plates of a stepper conveyor (its transmission is not shown).
The black square on each plate represents the dough before closing. At one position of the conveyor the dough is closed.
The dough after closing is shown in the left down corner of the video first scene.
The closing device consists of a cam drive and slider-crank mechanisms.
This mechanism may be used in following machine (see from 1.00 minute):
/watch?v=uHhJsCv2lxI