portfolio items with own permalink

Hi Kriesi Team,
I’ve got a question concerning the permalinks, that go along with each portfolio entry. I’ve created a page and named it “showreel”, to show some videos our company has made. Every spot is a separate entry with a separate portfolio page. Unfortunately, every portfolio page is named like this in the permalink:

name of my page/portfolio-item/name of video 1
name of my page/portfolio-item/name of video 2 etc.

I would like to have it this way:
name of my page/showreel/name of video 1

I came across a forum entry, that focuses on the same problem.
https://kriesi.at/support/topic/portfolio-items-permalink-and-breadcrumbs/
But I couldn’t find a proper solution for me.

My questions are:
a) is it possible, to change portfolio permalinks simply in the programming back-end? Change php code etc..?
b) can it be done via a plugin?
c) or am I forced to create my own custom post type, like Davin suggested it? (#163128) Can it have the same functionality like the classic portfolio? It seems to me that this is the most elaborate solution, because I would have to create the post type and re-create each portfolio entry new.

Thank you for your answer and best regards.