It would have been nice for you to show the correct way to ADJUST the cable set connecting the handbrake cable. Once you replace the cable, adjustments are required to reset to factory spec. Not everything goes this easily.
Unfortunately, we don't have the same video for Mercedes-Benz W203 but we recommend you to have a look at the playlist for MERCEDES-BENZ C (W203) : ru-vid.com/group/PLWep5LzT0sxm6eVaAWa7UqJCM9G7XRFJP
What is the ceramic grease product that you use in this and other repair videos? Can you provide a link? It would also be great if you could provide torque values. Thanks!