The S7-300 that I have has two DSub9 connectors. The one on the right is for PROFIBUS DP and the one on the left is for MPI. Communication with the programing tool is normally through MPI. Neither your video nor you pictures let see where you have connected the USB-MPI converter because the cover is closed, but it looks like you connected in on the right. I would advice you to confirm that you have connected the converter to the MPI port, not PROFIBUS.