Hi Ahmet. I ran your code straight out the box on ubuntu 18.04 with all necessary prerequisite installed, it displayed this:
Writing frame 1 / 7717
Writing frame 2 / 7717
Writing frame 3 / 7717
Writing frame 4 / 7717
Writing frame 5 / 7717
Writing frame 6 / 7717
Writing frame 7 / 7717
Writing frame 8 / 7717
Writing frame 9 / 7717
Writing frame 10 / 7717
Writing frame 11 / 7717
Writing frame 12 / 7717
but infact did not write the frames to system. No display windows showed without bounding box around faces either.